Is it valid to stipulate a term for a Salam contract based on the lunar cycle observation (Ahillah)?

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The term stipulated in a Salam contract must be ascertainable by the sighting of the new moon, such as the beginning, middle, or end of a month, or a specific known day within the lunar cycle. There is no disagreement regarding the validity of stipulating the term in this manner. This is evidenced by the statement of Allah the Almighty: "They ask you about the new moons. Say, 'They are signs for the people and for the Hajj'" (Quran 2:189). It is permissible to specify the term as being until Eid al-Fitr, Eid al-Adha, the Day of 'Arafah, 'Ashura, or similar fixed Islamic occasions because these are known through the lunar cycle.