Woe be to thee, you have broken the neck of your friend, you have broken the neck of your friend-he said this twice. If one of you has to praise his friend at all, he should say: I think (him to be) so and Allah knows it well and I do not know the secret of the heart and Allah knows the destined end, and I cannot testify his purity against Allah but (he appears) to be so and so.
Sahih Muslim Book 55, Hadith 83
← Previous Hadith Strange are the ways of a believer for there is good in every affair of his and this is not the case with anyone else except in the case of a believer for if he has an occasion to feel delight, he thanks (God), thus there is a good for him in it, and if he gets into trouble and shows resignation (and endures it patiently), there is a good for him in it.

Sahih Muslim Book 55, Hadith 82 Next Hadith → Allah's Messenger, no person is more excellent than he after Allah's Messenger (ﷺ). Thereupon Allah's Apostle (ﷺ) said: Woe be to thee, you have broken the neck of your friend, and he said this twice. Then Allah's Messenger (ﷺ) said: If anyone has to praise his brother at all, he should say: I think him to be so and so, and even on this he should say: I do not consider anyone purer than Allah (considers).

Sahih Muslim Book 55, Hadith 84