Rashi on Deuteronomy 4:25/רש"י על דברים ד׳:כ״ה

1ונושנתם AND YE SHALL HAVE BEEN LONG [IN THE LAND] — He gave them a vague intimation that they would be exiled from it at the end of 852 years, according to the numerical value of the word ונושנתם, but He sent them into exile earlier, at the end of 850 years. He did this two years earlier than the numerical value of ונושנתם, in order that the prophecy should not be fulfilled in them “that ye shall utterly perish” (v. 26). This is the meaning of what is said, (Daniel 9:14) “And the Lord hastened in regard to the evil, and He brought it upon us, for the Lord our God is צדיק” — i.e., He acted charitably (צדקה) with us, in that He brought it (the evil) two years before its assigned time (Sanhedrin 38a; Gittin 88a).