Tafsir of At-Tawbah 9:45

(إِنَّمَا يَسْتَأْذِنُكَ) — that is, to refrain from participating— (الَّذِينَ لا يُؤْمِنُونَ بِاللَّهِ وَالْيَوْمِ الآخِرِ).

Specifying faith in these two [Allah and the Last Day] in both instances serves to signal that the motivation for Jihad, and the deterrent from it, is belief or lack of belief in them. Whoever believes in them fights for the sake of his religion and its monotheism, and killing in its path becomes easy for him due to what he hopes for in the Last Day of lasting bliss; whereas he who does not believe is detached from that. Furthermore, faith in these two necessitates faith in all that which is mandatory to believe in.

(وَارْتَابَتْ قُلُوبُهُمْ) — linked to the relative pronoun [the noun governed by the verb], and the preference for the past tense form is to indicate that this doubt has been realized and established— (فَهُمْ فِي رَيْبِهِمْ) — and their constant skepticism within their hearts— (يَتَرَدَّدُونَ) — meaning they are confounded. The root meaning of "hesitation" (taraddud) is the act of going back and forth, and it is intended here as a metaphor or metonymy for being confounded, because a confounded person cannot settle in one place.

The verse was revealed, as is narrated from Ibn Abbas (may Allah be pleased with them both), regarding the hypocrites when they sought permission to stay behind from Jihad without an excuse, and they were, according to some narrations, thirty-nine men. Abu Ubaid, Ibn al-Mundhir, and others narrated from him that the statement of the Exalted (لا يَسْتَأْذِنُكَ), etc., was abrogated by the verse in Surah an-Nur: (إِنَّمَا الْمُؤْمِنُونَ الَّذِينَ آمَنُوا بِاللَّهِ وَرَسُولِهِ) up to (إِنَّ اللَّهَ غَفُورٌ رَحِيمٌ). Thus, Allah granted the Prophet (may the blessings and peace of Allah be upon him) the choice between the two, so whoever went out [to battle] went out with merit, and whoever stayed behind, stayed behind without sin, if he so willed.