What is the ruling on performing Friday prayer behind an Imam who performed tayammum while he can find water?

The absence of water is not the only valid reason for performing tayammum. It is also permissible to perform tayammum when there is a fear of an increase in illness or a delay in healing due to the use of water, based on the Almighty's saying: "And if you are ill or on a journey or one of you comes from the place of relieving himself or you have contacted women and find no water, then seek clean earth and wipe over your faces and your hands." If the imam is ill and fears this, his prayer is valid. The Malikis, Hanbalis, Abu Hanifa, and Abu Yusuf permitted a person who has Wudu to pray behind someone who has performed Tayammum, though the Malikis consider it disliked, and the Hanbalis consider it preferable for the person with Wudu to lead the prayer.