What is the ruling on the marriage of a man who stipulated in his marriage contract that every woman he marries thereafter shall be divorced, and then he subsequently married, according to the four schools of thought?

Regarding the condition not to marry another woman or take a concubine: there are different schools of thought. It is not binding according to the Shafi'i school. It is binding according to Abu Hanifa and Malik, in which case a divorce or manumission occurs. As for the Hanbali school, divorce or manumission does not occur because of it, but the woman gains the right to annul the marriage, based on the saying of the Prophet, peace be upon him: "The conditions most worthy of fulfillment are those by which you make intimacy lawful."