وَمَا لَنَآ أَلَّا نَتَوَكَّلَ عَلَى ٱللَّهِ وَقَدْ هَدَىٰنَا سُبُلَنَا ۚ وَلَنَصْبِرَنَّ عَلَىٰ مَآ ءَاذَيْتُمُونَا ۚ وَعَلَى ٱللَّهِ فَلْيَتَوَكَّلِ ٱلْمُتَوَكِّلُونَ
Wa mā lanā allā natawakkala ʿala'llāhi wa qad hadānā subulanā · Wa la-naṣbiranna ʿalā mā ādhaytumūnā · Wa ʿala'llāhi fa'l-yatawakkali'l-mutawakkilūn
"And what is it with us that we should not trust in God? And He has already guided us to our ways. We shall surely endure the harm you do us. Let those who trust put their trust in God alone."
The messengers do not frame a statement. Mā lanā allā natawakkala — "what is it with us that we should not trust?"
I record this as an observation about the word order: the sentence takes trust out of being an attitude that must be defended and reverses what it is that requires explaining. The question asked is not "why do you trust"; it is "why should we not trust."
I record this as my own reading, and its ground is the pronoun: the sentence does not say "He guided us to the way"; it says "He guided us to our own ways." That is, guidance is mentioned not as a single route imposed from outside but as each one's finding of his own way.
And the distinction between the singular ṣirāṭ and the plural subul is worth recording: in the first verse of the sūra ṣirāṭi'l-ʿazīzi'l-ḥamīd was singular. In the same sūra, one singular and one plural. I give this distinction as an observation; I draw no ruling from it.
And the verb comes with emphasis: la-naṣbiranna — with a lām and a doubled nūn. A pattern of pledge as strong as la-azīdannakum in the seventh verse — there it was God's pledge, here the messengers'.
The object of the endurance is specified too: ʿalā mā ādhaytumūnā — "the harm you do us." That is, endurance is given not as an abstract virtue but as a pledge against something that has been named.