Pasadikasutta 20.8

20.8

So neva ussādetabbo na apasādetabbo; anussādetvā anapasādetvā sveva sādhukaṃ saññāpetabbo tesaññeva byañjanānaṃ nisantiyā.

Without flattering or rebuking, you should carefully persuade them by examining that phrasing.