Can you please explain the guidelines of praising others, and when it is permissible or when it is blameworthy? The Prophet, sallallaahu 'alayhi wa sallam, said that if anyone praises you, you should put dirt in his mouth. Please explain.

All perfect praise be to Allah, the Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad is His slave and Messenger.

Praising others is permissible with conditions that the scholars mentioned; and if any of these conditions is not met, it becomes forbidden.

The Hanafi scholar Al-Khaadimi said in his book Bareeqah Mahmoodiyyah:

"Praising others is permissible with five conditions:

First: one should not praise himself, because praising oneself is not permissible. Allah says (what means): {…do not claim yourselves to be pure; He is most knowing of who fears Him.} [Quran 53:32]...

Second: avoiding excess or exaggeration in praising (which leads to lying)...

Third: the person who is praised should not be dissolute. Perhaps if one praises him in order to get rid of his injustice or to get his right from him or from others through his help, it does not harm, because necessity renders what is forbidden permissible...

Fourth: the praiser knows that praising that person does not cause him to be proud of himself or become arrogant; he knows this through signs and indications…

Fifth: the praise should not be for a forbidden purpose or one that leads to corruption; such as praising the beauty of a beardless male or a female among non-Mahrams (permanently unmarriageable kin) to arouse them…"

Imam An-Nawawi said in Sharh Muslim on the hadiths that indicate forbidding praise:

"The forbiddance is understood to be in regard to exaggeration in praise and adding to the description, or praising someone who is feared to become self-conceited or the like if he hears the praise. However, if this is not feared for a person because he is quite pious and has a sound mind and deep knowledge, then it is not forbidden to praise him in his presence without exaggeration; rather, if this leads to a benefit, such as urging him to do good or to increase his good deeds, or to be persistent in doing it, or to encourage others to imitate him, then praising him is recommended."

There is no doubt that praise may lead to harming the praised person, especially if the praise is about a religious matter and the person who is praised is weak and can be lured by the praise to self-conceit. It is for this reason that the Islamic texts forbade praise in the presence of someone who is feared to be affected by it, as reported by Al-Bukhaari and Muslim from ‘Abdur-Rahmaan ibn Abi Bakrah, from his father, that a man praised another man in the presence of the Prophet whereupon the Prophet said, "Woe to you, you have cut your friend's neck (saying it three times)." He then said, "If one of you has to praise a person and there is no other option, then say, I regard him to be such-and-such, if you regard him as such, and Allah is the One Who takes him to account, and no one can testify about a person above Allah."

An-Nawawi said, "Another narration reads, 'You have cut off the man's back;' meaning that you have destroyed him. This is a metaphor for the cutting of the neck, which is killing, as both destroy a person. It refers to the destruction of the praised person in his religion, and perhaps his destruction in this worldly life as well because of becoming deceived by self-conceit."

Allah knows best.