Tafsir of Ash-Shu`ara' 26:106

( إذ قال لهم ) is an adverbial expression for the denial, in the sense that it represents a prolonged period of time during which what occurred from both sides took place until the completion of the matter, just as their denial is an expression of what emanated from them from the beginning of his call, peace be upon him, to its conclusion.

Some have claimed that ( إذ ) is for causation, meaning: they denied because he said to them: ( أخوهم نوح ), meaning their kinsman, as one says: "O brother of the Arabs" or "O brother of Tamim." Upon this is the saying: "They do not ask their brother when he summons them in times of calamity," as Burhan has stated. The pronoun refers to the people of Noah, though it has been said it refers to the messengers, and that brotherhood refers to homogeneity, yet this is contrary to the apparent meaning.

( ألا تتقون ) Allah, Mighty and Majestic is He, in that you worship other than Him.