Yaakov blesses his children that the Egyptian ruler should have mercy on them. The Aish Kodesh asks, why doesn't he bless them that no harm should befall them. Just as Hashem creates an expanding universe and tells it to stop expanding so too there are different types of salvations. Sometimes salvation comes from an expanding process. You go to the doctor who diagnoses an illness, procure the medicine etc... Sometimes, if there is no time for an expanding process, Hashem says enough to the expansion. The salvation must come immediately. This is the deeper meaning of Hashem creating the world with middas harachamim before middas hadin. The mercy of Hashem bring a salvation immediately without any process needing to unfold.