Gd states only part of Noah's glory to him, but praises him more highly when speaking about him in his absence; this avoids the appearance of flattery: Eruvin 18b
Rav Yehudah ex-communicated a Teacher of Torah about whom there were bad rumors, and Rav Yehudah was pleased that when he died he would be able to report that even to a scholar such as this he had not engaged in flattery: Moed Katan 17a
