Egypt made peace with Israel to (1) get the Israelis out of the Sinai, (2) get an annual allowance from America, and (3) stabilize conditions in Egypt. If Egypt could destroy all of Israel overnight, they would do it just as quickly as Iran or Syria. Egypt tries to keep Israel happy for the same reason Israel tries to keep America happy. Self interest.
UN to hold off on separate Afghan bombing probe for now (Reuters)
from the article: Egypt denies calling Israel an 'enemy state'