Ruling when doubting whether the initial Takbir was for Dhuhr or Asr prayer?
Chapter on the Description of Prayer
Al-Mughni
Book of Prayer
Primary text
The ruling for doubting whether the initial Takbir was for Dhuhr or Asr corresponds to the ruling for doubting the initial intention, as the specification of the prayer is a necessary condition (shart) which is nullified by the doubt.
Supporting text
There is an alternative consideration suggesting that the prayer should be completed as a supererogatory prayer, similar to the case where one begins an obligatory prayer when its prescribed time has not yet arrived.