ויוסף הוא השליט על הארץ הוא המשביר לכל עם הארץ (מקץ מב:ו)

The Shla HaKadosh zt’’l writes on the greatness of answering אמן. “One who concentrates on a bracha and responds with “Amein”, it opens a well that pours forth plenty of goods.”  As it says in the pasuk ויוסף הוא השליט על הארץ – the first letters equals 91 corresponding to the word אמן which also equals 91. In the merit of answering אמן one can have plenty (like Yosef had).