BUT I SAY, SURELY ISRAEL DID NOT KNOW, DID THEY: alla lego (3SPAI), me Israel ouk egno (3SAAI): (18; 3:26; 1 Corinthians 1:12; 7:29; 10:19; 11:22; 15:50)

The question in the Greek includes the negative me which calls for a negative answer. Robertson translates, “Did Israel fail to know?” The answer expected is “no.” Israel in its bigotry, claimed it had a monopoly on salvation in spite of the fact that Moses and Isaiah had predicted the salvation of the Gentiles. Did the Jews have no warning that the Gospel was to go forth to the Gentiles, to all the earth? And he gives 2 replies, the first from Moses (below) and the second from the prophet Isaiah (65:1).

AT THE FIRST MOSES SAYS: protos Mouses legei (3SPAI): (11:11; Deuteronomy 32:21; Hosea 2:23; 1 Peter 2:10)

What marvelous grace! When Israel rejected her Messiah, God sent the Gospel to the Gentiles that they might be saved. This was predicted by Moses in [Dt32:21]. Paul had mentioned this truth before in [Ro 9:22-26].

I WILL MAKE YOU JEALOUS BY THAT WHICH IS NOT A NATION BY A NATION WITHOUT UNDERSTANDING WILL I ANGER YOU: ego parazeloso (1SFAI) humas ep ouk ethnei, ep ethnei asuneto parorgio (1SFAI) humas: (1:21,22; Psalms 115:5-8; Isaiah 44:18-20; Jeremiah 10:8,14; 1 Corinthians 12:2; Titus 3:3)

Bold (662) (apotolmao from apó = an intensifier + tolmáo = to dare) means to dare very much, to be very bold and so to speak out boldly or  boldly declare.

Solomon records for example that...

The wicked flee when no one is pursuing, but the righteous are bold as a lion (Proverbs 28:1)

Paul quotes Isa65:1-2, which occurs in the context of God’s judgment on Israel (Isa64:8-12), of Gentiles being accepted into God’s household (Isa56:3-8) and of God restoring the remnant of Israel to himself (Isa65:8-9).

I WAS FOUND BY THOSE WHO SOUGHT ME NOT I BECAME MANIFEST TO THOSE WHO DID NOT ASK FOR ME: heurethen (1SAPI) (en) tois eme me zetousin (PAPMPD), emphanes egenomen (1SAMI) tois eme me eperotosin (PAPMPD): (9:30; Isaiah 65:1,2) (Isaiah 49:6; 52:15; 55:4,5; Matthew 20:16; 22:9,10; Luke 14:23; 1 John 4:19)

Found (2147) (heurisko gives us the English word "eureka" from an exclamation attributed to Archimedes on discovering a method for determining the purity of gold) means to learn location of something, either by intentional searching or by unexpected discovery to learn the whereabouts of something

Sought (2212) (zeteo) means to try to learn the location of something often by movement from place to place in process of searching. To attempt to learn something by careful investigation or searching. To seek information by thinking, meditating, reasoning.

Manifest (1717) (emphanes from epí = over, upon + phaíno = to shine) (See in depth study on verb form epiphaino) means literally to make to shine upon,  and metaphorically means to make apparent, manifest or known

Ask (1905) (eperotao, from epí = intensifies meaning + erotáo = to ask, inquire of, beg of) means to interrogate, question or inquire.

In Isaiah God declared...

"I permitted Myself to be sought by those who did not ask for Me; I permitted Myself to be found by those who did not seek Me. I said, 'Here am I, here am I,' To a nation which did not call on My name. "I have spread out My hands all day long to a rebellious people, Who walk in the way which is not good, following their own thoughts, (Isaiah 65:1,2)

Israel's stubborn refusal to believe led to the destruction of the city and its temple, followed by her worldwide, age-long dispersion and suffering among the nations.

ALL THE DAY LONG I HAVE STRETCHED OUT MY HANDS: holen ten hemeran exepetasa (1SAAI) tas cheiras mou: (Matthew 20:1-15; 21:33-43; 22:3-7; Matthew 23:34-37; Luke 24:47; Acts 13:46,47)

Through Isaiah God declared

 "I have spread out My hands all day long to a rebellious people, Who walk in the way which is not good, following their own thoughts, a people who continually provoke Me to My face, offering sacrifices in gardens and burning incense on bricks; who sit among graves, and spend the night in secret places; Who eat swine's flesh, And the broth of unclean meat is in their pots. Who say, 'Keep to yourself, do not come near me, For I am holier than you!' These are smoke in My nostrils, A fire that burns all the day. (Isaiah 65:2-5)

Solomon records a similar refrain...

"Because I called, and you refused; I stretched out my hand, and no one paid attention 25 And you neglected all my counsel, And did not want my reproof 26 I will even laugh at your calamity; I will mock when your dread comes,  (Proverbs 1:24-26)

Jeremiah agrees noting that...

And the LORD has sent to you all His servants the prophets again and again, but you have not listened nor inclined your ear to hear, (Jeremiah 25:4)

"(God speaking) Also I have sent to you all My servants the prophets, sending them again and again, saying: 'Turn now every man from his evil way, and amend your deeds, and do not go after other gods to worship them, then you shall dwell in the land which I have given to you and to your forefathers; but you have not inclined your ear or listened to Me. (Jeremiah 35:15)

Jesus echoes a similar sad cry...

"O Jerusalem, Jerusalem, who kills the prophets and stones those who are sent to her! How often I wanted to gather your children together, the way a hen gathers her chicks under her wings, and you were unwilling." (Matthew 23:37)

TO A DISOBEDIENT AND OBSTINATE PEOPLE: pros laon apeithounta (PAPMSA) kai antilegonta (PAPMSA): (Deuteronomy 9:13; 31:27; Jeremiah 44:4-6; 1 Thessalonians 2:16; 1 Peter 2:8)

Disobedient (544) (apeitheo from a = without + peítho = persuade) means literally not to allow one’s self to be persuaded. It describes one who refuses to be persuaded and so to willfully and perversely disbelieve. It conveys an attitude of unbelief and involves deliberate disobedience or conscious resistance to authority. Men do not avoid Christ because of insufficient facts but because of proud and unrepentant hearts. Paul says that Israel was continually (the present tense indicates this was their habitual practice) remained unpersuaded and disbelieving.

Obstinate (483) (anti-lego from anti = instead of  + lego = speak) means to speak against and so to oppose another, to decline to obey him (in this case the will of God, which is good and acceptable and perfect). It means to declare one’s self against another (God) or to refuse to have anything to do with Him. Again the present tense indicates that this was Israel's habitual practice year after year, in the face of God's lovingkindnesses and persistent seeking.

Moses records that...

"The LORD spoke further to me, saying, 'I have seen this people, and indeed, it is a stubborn people. (Deuteronomy 9:13)

"For I know your rebellion and your stubbornness; behold, while I am still alive with you today, you have been rebellious against the LORD; how much more, then, after my death? (Deut 31:27)

Samuel records a similar saga of Israel's disobedient and obstinate heart (on the occasion of Israel asking Samuel to appoint a king over them to judge them like all the Gentile nations)...

And the LORD said to Samuel, "Listen to the voice of the people in regard to all that they say to you, for they have not rejected you, but they have rejected Me from being king over them. Like all the deeds which they have done since the day that I brought them up from Egypt even to this day—in that they have forsaken Me and served other gods—so they are doing to you also. (1 Samuel 8:7,8)

Nehemiah adds that even in the face of God's abundant provision

"But they became disobedient and rebelled against Thee, and cast Thy law behind their backs and killed Thy prophets who had admonished them so that they might return to Thee, and they committed great blasphemies." (Nehemiah 9:26)

Luke records the same

"You men who are stiff-necked and uncircumcised in heart and ears are always resisting the Holy Spirit; you are doing just as your fathers did. Which one of the prophets did your fathers not persecute? And they killed those who had previously announced the coming of the Righteous One, whose betrayers and murderers you have now become (Acts 7:51,52)

Israel was persistently unyielding, disobedient, self-willed, fault-finding, contrary, contradicting people. Woe! Remember that this describes the majority of Israel in the Old Testament...for some reason many evangelicals have the misconception that most of Israel was saved because they were the "Chosen" people or they were "saved" out of Egyptian bondage and this equates with genuine heart circumcision but careful reading of Exodus 32 (and many other passages, like the book of Judges see notes) reveals otherwise. Deliverance from physical bondage did not equate with deliverance from the penalty and power of sin. And so verse like this one by Paul and a study of Hebrews chap 3-4 clearly indicate that Israel was largely lost and only a remnant was saved (Ro 11:4-5)

Denney comments;

“The arms outstretched all the day long are the symbol of that incessant pleading love which Israel through all its history has consistency despised. It is not want of knowledge, then, nor want of intelligence, but wilful and stubborn disobedience that explains the exclusion of Israel (meanwhile) from the Kingdom of Christ and all its blessings.”