"Remember forever His covenant, the word He commanded for a thousand generations. Rabbi Chiya bar Abba said to the leader of the generation, to the excellent one of the generation, as it is stated, 'Blow a horn in honor of the oil.' Be a commandment for a thousand generations. Rabbi Chiya said in the name of Rabbi Shmuel bar Nachman that it was fitting for nine hundred and eighty generations to have arisen who were worthy of standing, all of whom were wiped out in the generation of the Flood.
Thus, God said that He would give the circumcision after a thousand generations. And you will find that ten generations elapsed from Adam to Noah and ten generations from Noah to Abraham. Rav Huna said in the name of Rabbi Elazar, the son of Rabbi Yosi HaGelili, that the commandment was given for a thousand generations, and a thousand generations arose in thought to be created, but many of them were wiped out, 970 to be exact.
What is the reason that the commandment was given for a thousand generations? Six generations from Abraham to Moses, this is the commandment for a thousand generations, which is the Torah, and there is nothing other than the Torah, as it is stated, 'And God spoke all these words.' When you almost reach the point where the inheritance of the land before them is not breached by sixty thousand, when Shimon and Levi went and committed the deed in Shechem, what did their father say to them? 'You have troubled me to bring me into disrepute, and I am almost at the end of my days.'