וְד֥וֹר רְבִיעִ֖י יָשׁ֣וּבוּ הֵ֑נָּה כִּ֧י לֹא־שָׁלֵ֛ם עֲוֺ֥ן הָאֱמֹרִ֖י עַד־הֵֽנָּה׃
And in the fourth generation they shall come back hither; for the iniquity of the Amorite is not yet full.’
Read halakhic rulings (Jewish law) on Genesis 15:16: and classical halakhic sources.