The Prophet صلى الله عليه وآله said: When a believer passes upon the Ṣirāt1, he will say: In the name of Allāh, The Entirely Merciful, The Especially Merciful (Bismillah al-Raḥmān al-Raḥīm), whereupon the blaze of the fire is extinguished, and it says: Pass through, oh believer, for indeed your light (nūr) has put out my blaze.
1. al-Ṣirāt (الصراط) is the bridge, hair-line in width, which everyone will have to pass through it on the Day of Judgement.
Some traditions say some people will pass like lighting, some will pass quickly, some will pass walking, some will pass slowly while crawling, being burned by its flames in the process.
There’s a tradition in al-Kāfi, that describes the supplication that Imām ʿAlī عليه السلام would recite while making ablution – where he would wipe his feet and say: Oh Allāh, make my feet firm on the Ṣirāt on the day which many will slip and fall.
وقال النبي ( صلى الله عليه وآله ) : إذا مر المؤمن على الصراط ، فيقول : * ( بِسْمِ اللَّه الرَّحْمنِ الرَّحِيمِ ) * أطفئ لهب النار ، وتقول : جز – يا مؤمن – فإن نورك قد أطفأ لهبة