Jāmiʿal-Akhbār: From ibn Masʿūd:

From the Prophet صلى الله عليه وآله who said: One who desires for Allāh to save him from the nineteen guardians of Hell1, should recite In the name of Allāh, The Entirely Merciful, The Especially Merciful (Bismillah al-Raḥmān al-Raḥīm), for it consists of nineteen letters, and Allāh will make each letter from it [a means of protection] from each of them.

1. As mentioned in the Qur’ān, there are nineteen angels guarding the hell-fire, or more specifically, Saqar. “Over it (Saqar) are nineteen [angels]. And We have not made the keepers of the Fire except angels. And We have not made their number except as a trial for those who disbelieve – that those who were given the Scripture will be convinced and those who have believed will increase in faith and those who were given the Scripture and the believers will not doubt and that those in whose hearts is hypocrisy and the disbelievers will say, “What does Allah intend by this as an example?” Thus does Allah leave astray whom He wills and guides whom He wills. And none knows the soldiers of your Lord except Him. And mention of the Fire is not but a reminder to humanity.” (al-Muddaththir 74:30-31)

 جامع الأخبار  : عن ابن مسعود ، عن النبي ( صلى الله عليه وآله ) : من أراد أن ينجيه الله من الزبانية التسعة عشر ، فليقرأ * ( بِسْمِ اللَّه الرَّحْمنِ الرَّحِيمِ ) * فإنها تسعة عشر حرفا ، ليجعل الله كل حرف منها عن واحد منهم