Rabbi Shimon ben Yoḥai taught: When the Israelites departed from Egypt, to what were they comparable? To the son of a king who recovered from his illness. His caretaker said to him: ‘Let your son go to the academy.’ The king said to him: ‘My son has not yet regained his radiance, which changed due to his illness.
Rather, let my son be pampered and enjoy himself for three months with food and drink, and then he will go to the academy.’ So too, when the Israelites departed from Egypt, there were those among them who were marred from subjugation with mortar and bricks. The ministering angels said to Him: ‘This is the time, give them the Torah.’ The Holy One blessed be He said to them: ‘My children have not yet regained their radiance as a result of mortar and bricks.
Let them be pampered up to three months with spring water, manna, and quail, and thereafter I will give them the Torah.’ When? “In the third month” (Exodus 19:1).