Is it valid to stipulate a term for a Salam contract based on festivals unknown to Muslims?
Chapter on Guaranteed Salaf (Advance Payment) for a Specified Term
Al-Mughni
Book of Sales
Primary text
Stipulating the term based on festivals unknown to Muslims, such as Sha'banin or Eid al-Fitir (the scattering of bread festival), is not permissible because Muslims do not know them. It is not permissible to follow the reckoning of the Dhimmis (People of the Book) in this matter, as their reckoning is not accepted, and they advance or delay these dates according to a calculation unknown to Muslims.