Аль-Исра 17:65

(2) Secondly, he had said if he was given respite till the day of Qiyamah, he will mislead the entire progeny of 'Adam, except a few of them. That Allah Ta’ ala has elected to answer in the later verses. He said that the Shaitan will have no control over His sincere servants even if he were to rally his entire forces against them and as for the insincere who fall into his trap, they will meet the same fate as his, all consigned to Hell. When this verse (64) mentions the horsemen and footmen of the Shaitanic army, it does not necessarily mean that the Shaitan actually has combat support in that formation. In fact, this is a manner of referring to the full force and power of the Shaitan. And if the Shaitan does have horsemen and footmen actually, even that too cannot be denied. Sayyidna ` Abdullah ibn ` Abbas ؓ said: Those who come out in support of disbelief and sin, horsemen or footmen, they are nothing but the army of the Shaitan. Now remains the question as to how the Shaitan came to know that he would succeed in enticing and misleading the progeny of 'Adam (علیہ السلام) ، the basis on which he claimed that he will subdue them. There are two possibilities. Perhaps, by looking at the ingredients that went into the making of man, he had gathered that man would be desire-prone and it would not be difficult to entice him successfully. And then, it is also not far out to believe that his very claim was nothing but a bland lie.

As for the sense of: وَشَارِ‌كْهُمْ فِي الْأَمْوَالِ وَالْأَوْلَادِ (and share with them in their wealth and their children - 64), Sayyidna ` Abdullah ibn ` Abbas ؓ said: Wealth and property acquired by false, impermissible and unlawful means or spent on what is haram is the sharing of the Shaitan in it. As for the sharing of the Shaitan in children, it could either be through illegitimacy, or by naming them like disbelievers and polytheists, or by indulging in polytheistic customs to ensure their security, or by taking to Haram sources of income to bring them up. (Qurtubi)