What is the ruling on ceasing to pay 15% of the total profits of a commercial project, knowing that the questioner had initially intended to pay it, then stopped doing so and offered expiation for an oath?

A person's statement: "Any money that comes to me from the company, I will take out 15% of it as a form of trade with Allah," is a metaphor and does not constitute a vow unless it is accompanied by a firm intention. If he intended it as a vow, then he must fulfill it; otherwise, there is no sin upon him for not fulfilling it. The reward and recompense are attained in all cases. Once a vow is made, it becomes obligatory to fulfill it. If one is unable to do so, an expiation for breaking an oath becomes due. The vowed percentage is to be given out according to the wording or the intention. If nothing was specified, the default is the exoneration of the responsibility, and only the minimum (the profit) is obligatory. If his vow was made and he did not fulfill it despite being able to, that might be a reason for a constriction in sustenance, otherwise not. Poverty and constriction in sustenance are trials from Allah for His servants.