✅Answer: There is no permission in the narrations for insulting and cursing oneself, and therefore this action has no place. However, the idea that a person should always see themselves as worse than everyone else and not consider themselves better than others is seen in the following narrations:

قال الصادق فِی حَدِیثٍ :وَمَنْ ذَهَبَ یَری أَنَّ لَهُ عَلَی الاْآخَرِ فَضْلاً، فَهُوَ مِنَ الْمُسْتَکْبِرِینَ فَقُلْتُ لَهُ إِنَّمَا یَری أَنَّ لَهُ عَلَیْهِ فَضْلاً بِالْعَافِیَةِ إِذَا رَآهُ مُرْتَکِباً لِلْمَعَاصِی فَقَالَ: «هَیْهَاتَ هَیْهَاتَ، فَلَعَلَّهُ أَنْ یَکُونَ قَدْ غُفِرَ لَهُ مَا أَتی وَأَنْتَ مَوْقُوفٌ مُحَاسَبٌ أَمَا تَلَوْتَ قِصَّةَ سَحَرَةِ مُوسَی علیه السلام؟

📚Al-Kafi, Vol. 8, p. 128

Translation: Imam Sadiq (peace be upon him) said in a hadith to Hafs: Whoever sees superiority and excellence for himself over another is one of the arrogant. Hafs said: He sees superiority and excellence for himself over another because he is in a state of 'afiyah' (well-being, free from sin) while he sees his counterpart committing sins! The Imam said: Far be it, far be it! Perhaps that person's sin will be forgiven while you are held back and held accountable. Have you not recited the verses of the story of the magicians of Pharaoh?!

✅Meaning, the outcome of the matter is what is important, and we cannot consider ourselves better than people who commit sins because of the 'afiyah' we currently have from sin.

أَبِی جَعْفَرٍ قَالَ قَالَ رَسُولُ اللَّهِ لَمْ یُعْبَدِ اللَّهُ عَزَّ وَ جَلَّ بِشَیْ ءٍ أَفْضَلَ مِنَ الْعَقْلِ وَ لَا یَکُونُ الْمُؤْمِنُ عَاقِلًا حَتَّی تَجْتَمِعَ فِیهِ عَشْرُ خِصَالٍ الْخَیْرُ مِنْهُ مَأْمُولٌ وَ الشَّرُّ مِنْهُ مَأْمُونٌ یَسْتَکْثِرُ قَلِیلَ الْخَیْرِ مِنْ غَیْرِهِ وَ یَسْتَقِلُّ کَثِیرَ الْخَیْرِ مِنْ نَفْسِهِ وَ لَا یَسْأَمُ مِنْ طَلَبِ الْعِلْمِ طُولَ عُمُرِهِ وَ لَا یَتَبَرَّمُ بِطِلَابِ الْحَوَائِجِ قِبَلَهُ الذُّلُّ أَحَبُّ إِلَیْهِ مِنْ الْعِزِّ وَ الْفَقْرُ أَحَبُّ إِلَیْهِ مِنَ الْغِنَی نَصِیبُهُ مِنَ الدُّنْیَا الْقُوتُ وَ الْعَاشِرَةُ لَا یَرَی أَحَداً إِلَّا قَالَ هُوَ خَیْرٌ مِنِّی وَ أَتْقَی إِنَّمَا النَّاسُ رَجُلَانِ فَرَجُلٌ هُوَ خَیْرٌ مِنْهُ وَ أَتْقَی وَ آخَرُ هُوَ شَرٌّ مِنْهُ وَ أَدْنَی فَإِذَا رَأَی مَنْ هُوَ خَیْرٌ مِنْهُ وَ أَتْقَی تَوَاضَعَ لَهُ لِیَلْحَقَ بِهِ وَ إِذَا لَقِیَ الَّذِی هُوَ شَرٌّ مِنْهُ وَ أَدْنَی قَالَ عَسَی خَیْرُ هَذَا بَاطِنٌ وَ شَرُّهُ ظَاهِرٌ وَ عَسَی أَنْ یُخْتَمَ لَهُ بِخَیْرٍ فَإِذَا فَعَلَ ذَلِکَ فَقَدْ عَلَا مَجْدُهُ وَ سَادَ أَهْلَ زَمَانِهِ

📚Al-Khisal, Vol. 2, p. 433

Translation: Imam Baqir (peace be upon him) said: The Messenger of Allah (peace be upon him and his family) said: Allah, the Mighty and Exalted, has not been worshipped with anything better than intellect, and a believer is not wise until ten characteristics are combined in him: good is hoped for from him, safety from his evil is guaranteed, he considers a little good from others to be a lot, and a lot of good from himself to be little, he does not tire of seeking knowledge his whole life and does not get bored or lose patience with those who ask him for a need, humility is more beloved to him than honor, and poverty is more beloved to him than self-sufficiency, his share of this world is only what is sufficient for his sustenance, and the tenth point is: he does not see anyone unless he says: He is better and more pious than me, for indeed people are of two types; one is better and more pious than him, and the other is worse and lower than him, so when he sees someone who is better and more pious than him, he humbles himself before him to join him, and when he meets someone who is worse and lower than him, he says: Perhaps the goodness of this person is in his inner self and his evil is in his outward appearance, and perhaps his matter will end well. So when he does this, his greatness is elevated and he becomes the leader of the people of his time.

✅Imam Kazim (peace be upon him) said: A man from the Children of Israel worshipped Allah for forty years, then he offered a sacrifice, but it was not accepted from him, so he said to himself: This has not befallen you except from yourself, and there is no sin except from you. Then Allah, the Blessed and Exalted, revealed to him: This self-blame you have made is better than your forty years of worship.

📚Al-Kafi, Vol. 2, p. 73

✅We must always, for every action, including self-blame, use phrases that are permitted in the narrations and not invent anything from ourselves in any religious matter, and for example, not send curses upon ourselves. There are many narrations and supplications on this topic that are too numerous to mention in this brief text, and what is important is that a person bases all his actions on the narrations.