Is the Adhan valid if the speaker has a speech impediment (Lathgh)?
Chapter on Adhan
Al-Mughni
Book of Prayer
Primary text
If the caller has a speech impediment (Lathgh) that is not excessive, his Adhan is permissible. It is narrated that Bilal used to substitute the seen for the sheen, saying 'As'had'.
Supporting text
If the person is able to overcome this speech impediment, it is considered more complete and better.