The saying 'the dye of Allah' is a source that is confirmed and stands upon His saying: 'We have believed in Allah,' just as 'the promise of Allah' stands upon what preceded it. It is a 'noun of action' from dyeing, like 'the sitting' from 'to sit.' It is the state that dyeing occurs upon, and the meaning is: the purification of Allah, for faith purifies the souls. The origin of this is that the Christians used to immerse their children in yellow water which they called baptism, and they said: it is a purification for them. When one of them did this to his child, he would say: now he has truly become a Christian. So the Muslims were commanded to say to them: say 'We have believed in Allah,' and 'We have been dyed by Allah with faith, a dye unlike our dye,' and 'We have been purified by it, a purification unlike our purification.' Or the Muslims may say: 'We have been dyed by Allah with His dye and we have not dyed with your dye.' The term 'dye' is used in a way of similarity, just as you would say to someone planting trees: plant as so-and-so plants, meaning a man who practices generosity. And who is better than Allah in dyeing? This means that He dyes His servants with faith and purifies them from the evils of disbelief, so there is no dye better than His dye. And His saying 'and we are worshippers of Him' is an addition to 'We have believed in Allah.' This addition refutes the claim of those who said that 'the dye of Allah' is a substitute for 'the religion of Abraham' or is in the accusative case as an exhortation meaning: you have the dye of Allah, due to the disruption of the structure and the removal of the speech from its coherence and consistency. The establishment of it as a confirmed source is what Sibawayh mentioned, and the saying is what Hudham said.