Surah 68. Al-Qalam, Ayah 18

I.e., they resolved upon their objective without the reservation, "if God so wills points to the first lesson to be derived from this parable, as well as to its connection with the rhetorical question in verses {14-15} above.

 Another possible translation: “… without leaving some for the poor.”

We must always remember, in all our plans, that they depend for their success on how far they accord with Allah's Will and Plan. His universal Will is supreme over all affairs. These foolish men had a secret plan to defraud the poor of their just rights, but they were put into a position where they could not do so. In trying to frustrate others, they were themselves frustrated.