This was said by the Buddha, the Perfected One: that is what I heard.

“Taking into account exterior factors, mendicants, I do not see a single one that is so very helpful as good friendship for a trainee mendicant who hasn’t achieved their heart’s desire, but lives aspiring to the supreme sanctuary from the yoke. A mendicant who has good friends gives up the unskillful and develops the skillful.”

The Buddha spoke this matter. On this it is said:

“A mendicant with good friends
 is reverential and respectful 
when their friends are speaking, 
aware and mindful. 
Gradually they would attain 
the ending of all fetters.”

This too is a matter that was spoken by the Blessed One: that is what I heard.