Prohibition of obscenity

It is narrated from Sayyiduna Anas (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "Whatever two people who insult one another say (against each other), its burden is on the one who started the insulting, so long as the wronged one does not exceed his limit (in taking revenge)."
And Imam Abu Ya'la said: Abu Ali narrated this report to us from Yunus with this same chain.

It is narrated from Sayyiduna Abu Umamah bin Sahl bin Hunayf (may Allah be pleased with them both) that the Messenger of Allah (peace and blessings be upon him) said: "None of you should ever say: 'Khabuthat nafsi' (My soul has become foul), but rather let him say: 'Laqisat nafsi' (My disposition has become troubled, or I feel nauseous)."
I (Ibn Hajar) say: This hadith is sahih (authentic). Imam al-Nasa'i narrated it in 'al-Yawm wa al-Laylah' through Qutaybah from Sufyan, while the two Shaykhs (Bukhari and Muslim) and other hadith scholars recorded it through the route of Yunus bin Yazid from al-Zuhri, from Abu Umamah bin Sahl, from his father (Sayyiduna Sahl bin Hunayf) (may Allah be pleased with him); and both these narrations are sahih (authentic). Sayyiduna Abu Umamah (may Allah be pleased with him) saw the Prophet and narrated from him, and his father was a Companion. Something related to this chapter has already been mentioned in the section on the virtue of modesty.

It is narrated from Sayyiduna Jabir (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "Do not revile the night and the day, nor curse the sun, the moon and the winds, for indeed these (phenomena of nature) are sent as a mercy for some people and as a punishment for others."
Imam Abu Ya'la narrated it.

It is narrated from Sayyiduna Ali bin Abi Talib (may Allah be pleased with him) that he used to say: "The one who utters obscene and indecent speech and the one who listens to it (attentively) are equal in the burden of sin."
Imam al-Bukhari narrated this report in al-Adab al-Mufrad (324) and Ibn Abi Shaybah in al-Musannaf (25547). Its narrators are thiqat (trustworthy), but Hassan bin Kurayb's hearing from Sayyiduna Ali (may Allah be pleased with him) is not established.

It is narrated from Ubaydullah (may Allah have mercy on him) that he saw Sayyiduna Usamah (may Allah be pleased with him) praying beside the blessed grave of the Messenger of Allah (peace and blessings be upon him). Marwan bin al-Hakam came out (from there) and said: "Are you praying beside his grave?" He replied: "Indeed, I love him." At this, Marwan said something extremely indecent and harsh to him, and then turned his back and left. Sayyiduna Usamah (may Allah be pleased with him) finished his prayer and said to Marwan: "You have certainly hurt me with your words, whereas I heard the Messenger of Allah (peace and blessings be upon him) say: 'Indeed, Allah Almighty hates the foul-mouthed one who speaks obscenely,' and you are certainly a foul-mouthed, obscene person."
The chain of this hadith is hasan (good). Imam Ahmad recorded it in his Musnad (21791), and Ibn Abi Asim in 'al-Ahad wa al-Mathani' (897).

It is narrated from Sayyiduna Imran bin Husayn (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "Cursing a believer is like killing him, and when a person says to his (believing) brother: 'O disbeliever,' then this (declaring him a disbeliever) is also like killing him."
Imam Ahmad bin Mani' recorded this hadith, and its basis is found in Sahih al-Bukhari (6105) and Sahih Muslim (110) through the narration of Sayyiduna Thabit bin al-Dahhak (may Allah be pleased with him), on account of which this hadith is sahih (authentic).

It is narrated from Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) that a rooster crowed in the presence of the Prophet (peace and blessings be upon him), and a man (annoyed by it) said: "O Allah, curse it." At this the Prophet (peace and blessings be upon him) said: "Do not revile it and do not curse it, for it wakes (people) for the prayer."

Imam Abd bin Humayd (may Allah have mercy on him) recorded a similar narration with his chain from Sayyiduna Abu Hurayrah (may Allah be pleased with him).
And the technically correct position is that this narration is from Ubaydullah, from Sayyiduna Zayd bin Khalid (may Allah be pleased with him).

It is narrated from Sayyiduna Anas (may Allah be pleased with him) that we were present with the Messenger of Allah (peace and blessings be upon him) when a flea bit a man and he cursed it. At this the Prophet (peace and blessings be upon him) said: "Do not curse it, for it woke one of the prophets of Allah for the prayer."
Imam al-Tabarani recorded in al-Mu'jam al-Awsat from Sayyiduna Anas (may Allah be pleased with him) that fleas were mentioned in the gathering of the Prophet (peace and blessings be upon him), and he (peace and blessings be upon him) said: "Indeed, they are a means of waking (people) for the prayer."

It is narrated from Sayyiduna Ali bin Abi Talib (may Allah be pleased with him) that we halted at a place, and there the fleas troubled us greatly, so we began to revile them. The Messenger of Allah (peace and blessings be upon him) said: "Do not insult them, for what an excellent creature it is, that it woke you for the remembrance of Allah Almighty."
This hadith is narrated from Sayyiduna Ali (may Allah be pleased with him) only through this chain, and the narrator named Adam is alone in transmitting it.

It is narrated from Sayyiduna Anas (may Allah be pleased with him) that a man was travelling with the Prophet (peace and blessings be upon him), and during this he cursed his camel. The Prophet (peace and blessings be upon him) said to him: "O servant of Allah! Do not travel with us on a camel that has been cursed."
Imam al-Tabarani stated in 'al-Mu'jam al-Awsat' (no. 2021/2): al-Abbas bin al-Fadl al-Asfati narrated to us, from Isma'il bin Abi Uways, who transmitted this narration with the same preceding chain, and he said that Isma'il is alone in narrating it.