Praise be to Allah, and peace and blessings be upon our master, the Messenger of Allah.

It is religiously recommended (Mustahabb) for a seller to accept a buyer's request to revoke a transaction if the buyer regrets the purchase. This is because the Messenger of Allah ﷺ said: "If anyone rescinds a sale with a Muslim, Allah will cancel his slip, on the Day of Resurrection" (Narrated by Abu Dawud).

Legally, a revocation (Iqalah) is considered the annulment (Faskh) of the original contract rather than the initiation of a new one. Consequently, the seller takes back the merchandise, and the buyer takes back the exact price paid. This concept of revocation is valid and applicable in the sale of gold. Shaykh al-Islam Zakariyyah al-Ansari (may Allah have mercy on him) stated: "Branching out from the ruling that it [revocation] is an annulment, several legal matters arise. Thus, it is permissible for the two parties to separate from the session of revocation in currency exchange (Sarf) before mutual possession takes place" [Asna al-Matalib fi Sharh Rawd al-Talib, Vol. 2/P.74].

Therefore, the seller takes back the gold at the price it was originally sold for, not at today's market price. Since the revocation is an annulment, the buyer only retrieves the exact sum of money they initially paid. However, this is contingent upon the condition that such a return was not stipulated as a choice or option during the initial contract, because a currency exchange contract (Aqd al-Sarf) cannot accommodate a contractual option of cancellation (Khiyar al-Shart).

In conclusion, there is no religious objection to a revocation (Iqalah) in the sale of gold, and the buyer shall retrieve only the exact price that they paid at the time of purchase. And Allah the Almighty knows best.