First, after he hears his brothers express regret for how they treated him:
They did not realize that Joseph was listening, since they [had spoken to him] through a translator. Joseph left them and wept. When he returned, he spoke to them sternly again.
Later, after Joseph sees his younger brother, Benjamin:
Joseph rushed out. His emotions had been aroused by his brother, and he had to weep. He went to a room and there he wept. He washed his face and came out. Holding in his emotions, he said, 'Serve the meal.'
In this week's Ten Minutes of Torah, Rabbi Charles A. Kroloff writes about Joseph's inability to cry in front of others (an inhibition he will overcome next week) and discusses why we shouldn't be afraid to express emotions through tears. Click here to read his commentary.
Now when Pharaoh let the people go, God did not lead them by way of the land of the Philistines, although it was nearer; for God said, "The people may have a change of heart when they see war, and return to Egypt." - Exodus 13:17