Q. I would like to know if someone is praying Salaatul Tasbeeh and Zawaal time comes in, will his Salaatul Tasbeeh be valid? And if Zuhr starts at 12:05, how much minutes before and after Zawaal time should be observed before Zuhr time comes in?
A. If someone is performing Salaatul Tasbeeh, and Zawaal time comes in (upon him) while he is still in Salaat, then his Salaah will be invalid (and broken).
Regarding this, the following is written in the famous book of Fiqh, Al Hidaya. It states:-
‘Salaah’ is not permissible at the time of the rising of the sun, at the time of Zawaal and at the time of the setting of the sun. This is based on the Hadith of Uqba bin Amir (RA) in which he said, ‘Three timings are such that the Prophet (SAS) has prohibited us from performing Salaah and burying our (dead) (that is, Salaatul Janaza) in them (i.e. in these three timings). These are, at the rising of the sun until it rises, and at Zawaal until the sun leans and moves (on one side) and when the sun sets.’ (Muslim) (Al Hidaya vol.1 pg. 82).
While commenting on the above text, many of the Fuqaha (jurists) have stated that the above prohibition includes the Farz Salaah and the Nafl (optional) Salaah. (Fathul Qadeer).
Based on this, it means that your Salaatul Tasbeeh will be invalid, and you will need to repeat it at a proper time.
If one wishes to perform optional Salaah before Zawaal, then he should stop a few minutes before the actual Zawaal time (say about 5 minutes). After Zawaal, a person should wait for about 5 minutes before he begins the Zuhr Salaah.
And Allah knows best.
Mufti Waseem Khan