Likutei Moharan 20:3/ליקוטי מוהר"ן כ׳:ג׳

13. And there is a difference between the lessons a person explains to himself and those he explains to a group of people. This is because when he expounds publicly, and before giving the lesson binds himself with their souls and pours out his words and prayers before God, then certainly (Job 36:5), “Behold, God is great and despises not.” But the prayers of an individual—perhaps they do despise his prayers.

2This corresponds to (Numbers 20:8), “Speak to the boulder in their presence”—your prayer should be at a time when the congregation is assembled <before you>. And this is (Deuteronomy 31:12), “Gather together the people.”