Jacob sent his sons – except Benjamin – to Egypt to buy grain. Joseph recognized them, but they did not recognize him. He devised a plan to see if they were ready to accept him as Jacob’s successor: He threatened not to receive them next time without Benjamin. Once Benjamin would be in Egypt, Joseph would invent an excuse to keep him there. If the brothers would be prepared to fight for Benjamin, it would mean that they had overcome their jealousy of Rachel’s sons. Jacob was reluctant to send Benjamin, but his other sons convinced Jacob that they had no choice. So Jacob agreed, but first prayed for their success.
Natural Miracles
וְאֵל שַׁדַּי יִתֵּן לָכֶם רַחֲמִים לִפְנֵי הָאִישׁ וגו': (בראשית מג:יד)
[After preparing a gift to send to Joseph, Jacob prayed,] “May G-d Almighty grant that the man be merciful to you.” Genesis 43:14
Conventional wisdom has it that prayer is necessary only in desperate situations. Thus, Jacob’s sons assumed that since Joseph was detaining their brother because he suspected them of being thieves or spies, it would be enough to pacify him with a gift.

From Jacob’s words to his children, however, we learn that even when a favorable outcome seems perfectly natural, we should never assume that we can reach it without Divine assistance. We must always pray – and not as a secondary measure, but as the primary measure.

Although we must create natural channels to facilitate G‑d’s blessings, we should realize that G‑d, who is beyond nature, controls every aspect of our lives. When we realize this fully, we will indeed perceive that the “natural” occurrences of our lives are all in fact miracles garbed in nature.1

FOOTNOTES
1. Likutei Sichot, vol. 25, pp. 227–234.