This is probably while the scribes and Pharisees were looking for a way to trap him. The author uses these words to mark the beginning of a new event. (See: [[rc://en/ta/man/translate/writing-newevent]])
This is probably an exaggeration to emphasize that so many people were crowded close together that they would step on each other. AT: "they were stepping on each other" or "they were stepping on one another's feet" (See: [[rc://en/ta/man/translate/figs-hyperbole]])
Just as yeast spreads through a whole lump of bread dough, their hypocrisy was spreading through the whole community. AT: "Guard yourself against the hypocrisy of the Pharisees, which is like yeast" or "Be careful that you do not become hypocrites like the Pharisees. Their evil behavior influences everyone just as yeast affects a lump of dough" (See: [[rc://en/ta/man/translate/figs-metaphor]])