يَا أَيَّتُهَا النَّفْسُ الْمُطْمَئِنَّة ارْجِعِي إِلَىٰ رَبِّكِ رَاضِيَةً مَرْضِيَّةً فَادْخُلِي فِي عِبَادِي وَادْخُلِي جَنَّتِيُ
Yā ayyatuhan-nafsul-muTma’innati-rji‘ī ilā rabbiki rādiyatam-maridyyah. Fadkhulī fī ‘ibādī wadkhulī jannatī
O soul at peace! Return to your Lord, well-pleased (with Him), well-pleasing (Him), So enter among My servants, And enter into My garden. (Sūratul Fajr, No. 89, Āyāt 27 – 30)
Sūratul Fajr has been called the Sūra of Imam al-Husayn (a). A Hadīth of Imam al-Sādiq (a) says: Recite Sūratul Fajr in your wajib and mustahab salāt for it is the sūra of Husayn bin Ali (a). Have a liking for it; may Allah have mercy on you.
According to Tafsir-e Namūne Sūratul Fajr is known as the Sūra of Imam Husayn (a) because of the following possible reasons:
1) The soul that is at rest, mentioned in the last verses, is manifested in Imam Husayn (a). His is the soul that was completely at rest amidst very trying circumstances.
2) The 10 nights mentioned in the second verse of the Sūra could be referring to the first 10 nights of Muharram.
The verses above are a call from the Lord to the soul that is completely at peace due to faith and complete trust in Him. Such a soul is tranquil and at rest, no matter what the world offers him. Whether in happy circumstances or unhappy ones, outer disturbances do not affect the peace that is at the core of the soul of the believer.
The soul is invited to return back to Allah, the place it originally came from. After we (all) belong to Allah and to Him we shall (all) return (Q 2:156). It is an invitation to return home, a home where God is the host. The call is to return to the Lord and to the blessings that He has prepared for the faithful believers. To enter the garden He has kept ready for them, and to be among the chosen servants of Allah, a blessing that is the ultimate honor for the believer.
The soul is rādiyah, well pleased with the mercy of the Almighty and the blessings it sees and receives. It is more than the soul ever imagined while in the world, and witnessing it in the Hereafter makes him pleased and happy. The soul itself is also mardhiyya, i.e. a soul that is accepted and pleasing to Allah. Its faith and deeds are accepted by God.
These verses denote the ultimate status granted to a believer, an invitation and an acceptance by the Lord Himself. No achievement can be greater than that. Knowing that at the end of life one has pleased the Lord and is invited to be close to Him brings extreme satisfaction. It is a fitting beginning to an eternal life of happiness.
As Muslims who remember Imam al-Husayn (a) often, we are in a better position to follow on the footsteps of al-Husayn such that our entire lives are dedicated in seeking the ultimate pleasure (ridā) of Allah. In the above Hadīth, Imam al-Sādiq (a) continues: and this surah is especially for al-Husayn b. Ali (peace be on both of them), his Shī‘ahs (followers) and the Shī‘ahs of the Family of Muhammad (a). How do we achieve this status? The Imam suggests: One who recites al-Fajr regularly [deriving inspiration from it] shall be in the rank of al-Husayn with him in Paradise. Indeed Allah is all-Mighty, all-Wise.
Sources: Aytaullāh Nāsir Makārim Shirazī (ed.), Tafsīr-e Namūneh;
Shaykh Abbās al-Qummīi, Nafas al-Mahmūm.