What is the ruling on a marriage that was solemnized by an officiant, a couple, a guardian, and two witnesses who do not pray, and in which the legal form of the contract was not mentioned? And is it considered Islamically valid if they repent and pray, or must the contract be redone?

One who abandons prayer is either denying its obligatory nature, and such a person is a disbeliever by scholarly consensus, or they abandon it out of negligence and laziness. Such a person is a disbeliever according to the more preponderant of the two scholarly opinions. If a couple marries while both are abandoning prayer, then they repent and start praying, they remain married and do not need to renew their marriage contract. The Prophet, peace and blessings be upon him, maintained the marriages of disbelievers who embraced Islam and did not order their renewal. This is what the scholars have agreed upon. As for the children, they are legitimate and are attributed to their fathers.