Praise be to Allah.
Cursing falls into two categories:
1 – Cursing the kuffaar and sinners in general terms. This is permissible as is indicated by the texts of the Qur’aan and Sunnah.
2 – Cursing an individual kaafir or evildoer concerning whom there is no text that speaks of cursing him. There is a difference of opinion concerning this among the scholars, but the correct view is that it is not allowed. See question no. 36674.
Cursing a great deal is criticized, because the Prophet (peace and blessings of Allaah be upon him) said: “The believer is not a slanderer, one who curses a great deal, one who indulges in obscenity or who in engages in foul talk.” Narrated by al-Tirmidhi (1977); classed as saheeh by al-Albaani in Saheeh al-Tirmidhi.
Al-Tirmidhi (2019) also narrated that Ibn ‘Umar (may Allaah be pleased with him) said: The Prophet (peace and blessings of Allaah be upon him) said: “The believer is not one who curses a great deal.” Classed as saheeh by al-Albaani in Saheeh al-Tirmidhi.
The Prophet (peace and blessings of Allaah be upon him) said that cursing a great deal is one of the causes of entering the Fire, as al-Bukhaari (304) and Muslim (80) narrated that Abu Sa’eed al-Khudri (may Allaah be pleased with him) said: The Messenger of Allaah (peace and blessings of Allaah be upon him) said: “O women, give in charity and pray a great deal for forgiveness, for I have seen that you are the majority of the people of Hell.” A wise woman among them said: Why is it, O Messenger of Allaah, that we are the majority of the people of Hell? He said: “You curse a great deal and are ungrateful (takfurna) to your husbands …
And Muslim (2599) narrated that Abu Hurayrah (may Allaah be pleased with him) said: It was said: O Messenger of Allaah, pray against the mushrikeen. He said: “I was not sent to curse, rather I was sent as a mercy.”
And Muslim (2597) narrated from Abu Hurayrah (may Allaah be pleased with him) that the Messenger of Allaah (peace and blessings of Allaah be upon him) said: “It is not appropriate for a sincere believer to be given to cursing.”
And Muslim (2598) narrated that Abu’l-Darda’ (may Allaah be pleased with him) said: I heard the Messenger of Allaah (peace and blessings of Allaah be upon him) say: “Those who curse a great deal will not be witnesses or intercessors on the Day of Resurrection.”
If the matter is as described in these ahaadeeth, then how can a Muslim accept this status for himself and accept to miss out on the status of the sincere believer, the witness and the intercessor on the Day of Resurrection?
Al-Nawawi (may Allaah have mercy on him) said in Sharh Muslim: It is not appropriate for the sincere believer to be given to cursing or for those who are given to cursing to be witnesses or intercessors on the Day of Resurrection. This is a rebuke that discourages cursing and a warning that the one who has this characteristic does not possess these beautiful attributes, for cursing is a kind of du’aa’ in which one prays that someone will be cast far away from the mercy of Allaah, and praying for such a thing is not the attitude of the believers whom Allaah has described as merciful to one another and as cooperating in righteousness and piety, and has made them like a structure, parts of which support other parts, and like a single body. The believer likes for his brother what he likes for himself. If a man prays that his brother be cursed, which means asking that he be cast far away from the mercy of Allaah, this is the ultimate in severing ties and turning one’s back on another, and this is the worst that the Muslim wishes for the kaafir, and prays against him. Hence it says in the saheeh hadeeth: “Cursing a believer is like killing him,” because the killer cuts him off from the benefits of this world, and this cuts him off from the blessings of the Hereafter and the mercy of Allaah, may He be exalted. And it was said that “Cursing a believer is like killing him” refers to the degree of sin, which is more likely. End quote.
What is mentioned in the texts about some types of sinners being cursed, such as the thief, the one who drinks alcohol and the one who consumes riba, is to be interpreted as being general in meaning, not referring to any specific person, according to the majority of scholars. But it is not permissible to curse a specific person, because of the ahaadeeth which say that cursing is not allowed, and because that involves insulting and causing annoyance, which may lead to despairing of the mercy of Allaah.
That includes the hadeeth referred to in the question, which was narrated by al-Tabaraani from ‘Abd-Allaah ibn ‘Amr (may Allaah be pleased with him), who said: I heard the Messenger of Allaah (peace and blessings of Allaah be upon him) say: “At the end of my ummah there will be women who are clothed yet naked, with something on their heads like the humps of camels; curse them for they are cursed.” Classed as hasan by al-Albaani in al-Thamar al-Mustataab (1/317) and in Jilbaab al-Mar’ah al-Muslimah (p. 125).
This is to be understood as a curse that is general in meaning, as stated above.
You should convey this advice to your brother, so that he will stop doing this, because even though it is not haraam, as is the view of the majority of scholars, at the very least it is dubious, and the Prophet (peace and blessings of Allaah be upon him) said: “Whoever guards against the doubtful matters will protect his religious commitment from shortcomings and will protect his honour from slander, but whoever falls into that which is doubtful will fall into that which is haraam.” Narrated by al-Bukhaari (52) and Muslim (1599).
Moreover the believer should be keen to guide people and show compassion towards them, striving to call them and save them. Cursing does not lead to any such thing, rather if the one who is prayed against hears about it, it will put him off even more and will make him feel more resentful. How good it is for a man to get used to praying for people, such as saying: May Allaah guide him, O Allaah, guide them aright, and so on, which is beneficial for the one who prays and the one for whom he prays. People’s hearts are between two fingers of the Most Merciful, and who can be sure that he is safe? If you have been guided then praise Allaah and hope for your brothers to be given the same blessings that you have been given. Remember the words of Allaah (interpretation of the meaning):
“Even as he is now, so were you yourselves before till Allaah conferred on you His Favours (i.e. guided you to Islam)”
What does this brother think of the words of the Messenger (peace and blessings of Allaah be upon him): “Whoever among you sees one who has been stricken with calamity and says, ‘Praise be to Allaah Who has spared me that with which He has tested you, and has favoured me over many of those whom He has created,’ Allaah will protect him from that calamity, no matter what it is, so long as he lives.” Narrated by al-Tirmidhi (3431); classed as hasan by al-Albaani in Saheeh al-Tirmidhi. This is the guidance of the Prophet (peace and blessings of Allaah be upon him); this is his Sunnah and his example, in word and in deed. So adhere to it, and you will be one of those who are successful and are saved.
May Allaah help us all to do that which He loves and which pleases Him.
And Allaah knows best.