Is a stipulation making the option period begin from the time of separation valid if the option duration is specified?

Chapter on the Option of the Two Parties in Sale

Al-Mughni

Book of Sales

Book 12 · Issue 3 · Bab 2

Open in Qurani

Primary text

If the parties agree that the option begins from the time of separation, but they stipulate its commencement should be from the moment of the contract, the stipulation is valid because the beginning and end points are made certain. This is preferred over the alternative.

Supporting text

It is alternatively suggested that this might not be valid because the option established in the contract session already suffices, thereby preventing the establishment of another one.