## God saw what they did ##

"God understood that they that they stopped doing evil actions"

## God changed his mind about the punishment which he had said he would do to them ##

"God changed his thinking about the punishment that he had said he would do to them" or "God decided not to punish them as he had said he would"

## and he did not do it ##

This can be translated more specifically: "and he did not punish them" or "and he did not destroy them."