Tafsir of Al-Fajr 89:27-29

{O soul} This implies an omitted verb of speech; that is, God says to the believer: {Do not kill the soul}. This speech may occur as an honor to the believer, just as He spoke to Moses (peace be upon him), or it may be conveyed through an angel.

{The tranquil (al-muṭmaʾinna)} The secure soul, which is neither provoked by fear nor grief. It is the believing soul, or the one tranquil in the Truth, settled by the coolness of certainty so that no doubt disturbs it. The reading of Ubayy ibn Ka‘b supports the first interpretation: "O soul that is secure and tranquil."

If you ask: When is this said to the soul? I say: It is said either at the time of death, at the Resurrection, or upon entering Paradise. It means: Return to the promise of your Lord.

{Satisfied} With what you have been given.

{Pleasing} To God.

{Enter among My servants} Join the ranks of My righteous servants and be included in their order.

{And enter My Paradise} With them.

Other interpretations:

• Some say "the soul" refers to the spirit, meaning: "Enter into the bodies of My servants."
• Ibn ‘Abbās read: "Enter among My servant" (singular).
• Ibn Mas‘ūd read: "Into the body of My servant."
• Ubayy read: "Come to your Lord, satisfied and pleasing; enter among My servant."
• Some say this verse was revealed regarding Hamza ibn ‘Abd al-Muṭṭalib.
• Others say it was revealed regarding Khubayb ibn ‘Adī, whom the people of Mecca crucified, turning his face toward Medina. He prayed: "O God, if I have any goodness with You, turn my face toward Your Qibla." God turned his face toward it, and no one could turn it back. However, the apparent meaning is general.