Musar su Esodo 14:27

You may well ask whence Earth knew all this, seeing that the original light was not hidden until after the first Sabbath, whereas Earth withheld part of her services already on the third day of creation? We must assume that G–d had certainly revealed this secret to Earth. Anyone who grants a gift planning to withdraw it later must inform the recipient of the gift that it is subject to recall at the time the gift is first granted. Bereshit Rabbah 5,5 states that G–d made a condition with the Ocean that when the Israelites would approach the Sea of Reeds in order to cross it, it would split and let the Israelites pass. The scriptural allusion is found in the words וישב הים…לאיתנו, "the sea returned to its contract" (Exodus 14,27). The word איתנ contains the same letters as the Hebrew word for "condition, contract" i.e. תנאי. We have numerous similar statements throughout the Midrash, all of which refer to G–d having imposed such "conditions" on different elements of the universe in order to have the right to interfere with the laws of nature through the performance of miracles whenever the need arises.