There are only seven NT epistles, books, letters,or whatever you want to call them, which do not quote the OT. This means that throughout the NT, the OT is quoted extensively. Israel was not asked to learn some new thing. There was no new thing introduced during the record of the Acts, instead, we find the OT is extensively quoted, reinforcing what they already should have known that it was, at that time, NOW that they as Israelites were to obtain unto 'the times of refreshing'. That gentiles would be used to provoke Israel to emulation was never a secret, that gentiles were to be blessed and witness for Israel was never a secret. There was no secret that Israel was to obtain during the Gospels, nor the Acts, so if we want to understand the outworking of God, and the administrations of God, we should want to know that this was no new instruction being given to Israel during the Acts, that gentiles were supposed to hear the word of truth without becoming an Israelite. And, in the NT, they were experiencing that which was foretold of THEM. The OT reveals that their choice could have gone either way, but that they would likely fulfill the most dreadful of all prophecy, namely Isa. 6:8-10; Hos. 3; &c.But, something happened. And the OT could no longer be quoted. And if we want to know what it was, and what is different, we should acknowledge that the Book mentions many other books that the Lord did not decide to include. Therefore, we have what the Lord DID intend for us to have, and this includes letters written 'at sundry times' (different times) to the children of God - in which there were different instructions depending upon which administration of God obtained.What is truth for today? Is it that the Lord came not but for the lost sheep of the house of Israel? Or was further truth unfolded after such and such a thing had happened, and what happened?