Is the guarantee valid if communicated through the gestures of a mute person?
Chapter on Guarantee (Daman)
Al-Mughni
Book of Assignment (Transfer of Debt)
Primary text
The guarantee of a mute person is valid if their gesture is understood, because their sales, confessions, and gifts are valid, placing their guarantee on par with that of a speaking person.
Supporting text
A guarantee is not established by writing alone if it lacks an understandable gesture indicating the intention to guarantee, as writing might be mere idle talk or an experiment. If the mute person's gestures are incomprehensible, the guarantee is invalid because their intent is unknown, and their other transactions are invalid.