قال الشيخ رحمه الله ولا يؤم المتيمم المتوضئين ولا يؤم المتوضى المتيممين وهذه المسألة مثل الاولى في ان الاولى ان لا يؤم المتيمم المتوضئين ولو فعل ذلك لم يكن بذلك مبطلا لصلاته لكنه يكون قد ترك الافضل فاما الذي يدل على كراهة ذلك ما رواه
The understanding of this hadith is that Imam عليه السلام only said, ‘If it is Dhuhr, let him make the obligatory prayer in the first two rak’ahs,’ because when he does so, it becomes permissible for him to make the last two rak’ahs into the Asr prayer. And when it is the Asr prayer, he makes the last two rak’ahs his prayer, because it is disliked to pray after Asr except as make-up (qadah). So, whoever prays as we have described, nothing remains upon him, and the (extra) rak’ahs are counted for him among the supererogatory (nafl) prayers. The Shaykh (Al-Mufid), may Allah سبحانه وتعالى have mercy on him, said: “A person performing tayammum should not lead those who have performed wudu, and likewise, one who has performed wudu should not lead those performing tayammum.” This matter is similar to the previous one, in that it is preferable that a person performing tayammum not lead those who have performed wudu. But if he does so, his prayer is not invalidated by that; rather, he has merely abandoned what is more virtuous.” As for what indicates the dislike (karahah) of that, it is what was narrated:
