Assalaamu alaykum. What does the following hadith mean? "Whoever prays Fajr, Allaah will protect him." Muslim

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah and that Muhammad is His slave and Messenger.

The hadeeth that you are asking about encourages Muslims to perform the Fajr prayer in congregation in order to be under the special protection of Allaah; whoever harms that person incurs the punishment of violating the protection of Allaah. It could also mean, "You should not neglect performing the Fajr prayer lest you break the covenant between you and your Lord."

Al-Munaawi wrote:

"The version of the hadeeth narrated by (Imaam) Muslim reads, 'Whoever performs the Fajr prayer in congregation is under the protection of Allaah; so let not Allaah call you to account.' The phrase 'in congregation' is used for the purpose of specifying the general indication of the sentence. 'Under the protection of Allaah' means that he is shielded with the covenant or safety or guarantee of Allaah. Hence, do not harm someone who has been granted the protection of Allaah; otherwise, you would incur His punishment. In the version of this hadeeth cited by At-Tirmithi, the last part reads, '...so do not betray Allaah by betraying those who are in His protection.' Ibn Al-ʻArabi commented, 'This does not mean that it is impossible to harm the person shielded by the protection of Allaah; rather, it means that if anyone does so, then Allaah will claim the wronged person’s right and punish him (the aggressor) for betraying His protection. It indicates that the punishment will take place, not that none can harm such a person."

Al-Baydhaawi wrote:

"The apparent indication of the hadeeth is forbidding the act of betraying the protection of Allaah (by harming those under His protection); however, the actual indication is forbidding them from incurring whatever entails violating the covenant of Allaah and betraying those who are under His protection. It was also said that the hadeeth means that one should not neglect performing the Fajr prayer, which entails earning the protection of Allaah; it means, 'Do not miss the Fajr prayer or neglect observing it as due lest you violate the covenant of protection between you and your Lord. Beware lest Allaah questions you about what you owe Him; for if He questions anyone of you and he falls short of fulfilling the duty that he owes Him, then He will requite and then throw him upon his face into the Hellfire. That is because the Fajr prayer is rather hard for people to observe; observing it is most likely an indication of the person’s sincere devotion to Allaah, and such a person is under the protection of Allaah ... The meaning of the hadeeth is that whoever performs the Fajr prayer is under the protection of Allaah; so do not harm him in the slightest lest Allaah would punish you, and His punishment can never be escaped." [Faydh Al-Qadeer]

Allaah knows best.