Is it permissible for someone afflicted with obsessive doubts (waswasah) to combine two prayers without a valid excuse, given that they do not find sufficient time to pray between lectures, and does that affect the validity of the prayer?

The Prophet, peace and blessings be upon him, combined two prayers in Medina so as not to cause hardship to his ummah. Scholars differed on the permissibility of combining prayers simply out of need. The majority of them prohibit it unless there is specific evidence, while the Hanbalis broadened it, making it permissible for any excuse or preoccupation that permits abstaining from Jumu'ah and congregation. Some Malikis, Shafi'is, Ibn Sirin, and Ibn Shubrumah held the view that combining prayers out of need is permissible as long as it does not become a habit. This latter view is adopted in cases of necessity, such as a doctor performing an operation. As for the Hanafis, they do not permit combining prayers for travel, illness, or other excuses, and their view is rejected due to its contradiction with the evidence. Obsessive-compulsive disorder (waswas) is not an excuse that permits combining prayers; rather, it is an illness.