The Egyptians embittered the lives of the Israelites with what the verse describes as “oppressive labor.” The Sages explain that the difficulty referenced pertained to the unstructured timing of the labor, and by forcing people to engage in labor that did not fit their skills.

In Egypt there were immigrants of seventy languages, but the Egyptians enslaved only the Israelites, as it is stated: “They embittered their lives with oppressive labor, with mortar and with bricks and with all work in the field” (Exodus 1:14). What is the meaning of: “And with all work in the field”? After an Israelite would perform labor with mortar and bricks and would come to rest in the evening in his home, an Egyptian would come and say to him: Go out and gather vegetables for me from the garden; or: Chop this wood for me; or: Fill this barrel with water for me. That is the meaning of: “And with all work in the field.” What is the meaning of: “With all their work with which they worked for them with travail” (1:14)? It is that they would give a man’s work to a woman and a woman’s work to a man. They would say to the man: Arise! Knead and bake! They would say to the woman: Fill this barrel! Chop this wood! Go to the garden, bring vegetables! (Tanĥuma, Vayetze)