It is narrated from Hazrat Abu Bakrah (may Allah be pleased with him) that once, in the presence of the Prophet (peace and blessings be upon him), a man praised another. The Prophet (peace and blessings be upon him) said, "Alas, you have broken your companion's neck." And he said, "If any of you must praise his brother, then he should say: 'I think that so-and-so appears to be such-and-such, and I do not declare anyone pure before Allah, and Allah is his true guardian, and I consider him as such.'"