Messenger of Allah ﷺ said, "For every prophet there is one (special invocation (that will not be rejected) with which he appeals (to Allah), and I want to keep such an invocation for interceding for my followers in the Hereafter."  

أَنَّ رَسُولَ اللَّهِ ﷺ قَالَ لِكُلِّ نَبِيٍّ دَعْوَةٌ مُسْتَجَابَةٌ يَدْعُو بِهَا وَأُرِيدُ أَنْ أَخْتَبِئَ دَعْوَتِي شَفَاعَةً لأُمَّتِي فِي الآخِرَةِ  

that the Prophet ﷺ said, "For every prophet there is an invocation that surely will be responded by Allah," (or said), "For every prophet there was an invocation with which he appealed to Allah, and his invocation was accepted (in his lifetime), but I kept my (this special) invocation to intercede for my followers on the Day of Resurrection."  

عَنِ النَّبِيِّ ﷺ قَالَ كُلُّ نَبِيٍّ سَأَلَ سُؤْلاً أَوْ قَالَ لِكُلِّ نَبِيٍّ دَعْوَةٌ قَدْ دَعَا بِهَا فَاسْتُجِيبَ فَجَعَلْتُ دَعْوَتِي شَفَاعَةً لأُمَّتِي يَوْمَ الْقِيَامَةِ