Likutei Moharan 34:3/ליקוטי מוהר"ן ל״ד:ג׳

13. This aspect of “Yosef was the ruler” corresponds to the m’loopum. As is written: The brit is the vehicle for Yesod, the HaVaYaH which is punctuated with a m’loopum. This is because the letters of M’LoopUM spell M’Lo PUM (a full mouth), indicating that the vessels of bounty—i.e., the tzaddik’s mouth—are filled with the Blessed One’s Godliness.

2For on the face of it, it is hard to understand why we have to pray when God knows [all our] thoughts. However, this is because words are the vessels of bounty, through which we receive the influx of bounty. As is written (Deuteronomy 1:11), “and bless you as He said to you”—i.e., the influx of bounty is in accordance with the speech. If the words, the vessels of bounty, are perfect and in fullness, then we can receive abundant bounty in them.

3And the words of the tzaddik are certainly [spoken] with perfection and fullness. Therefore, he can draw bounty to Israel. This is why he is called an aspect of “a full mouth,” to indicate that his mouth is full and perfect.