If during prayers one does something or remains silent for a while and doubts whether or not his prayer has broken up, he must perform the prayer again. However, it is better that he first complete that prayer and then repeat it. Tenth: eating and drinking. If one eats or drinks while performing prayers in a manner that it cannot be said he is performing prayers – irrespective of whether he does this intentionally or forgetfully – his prayer becomes invalid.
However, if before the time of ṣubḥ prayers a person who wants to fast performs a recommended prayer and becomes thirsty, then in the event that he fears that if he completes the prayer it will be time for ṣubḥ prayers, and if there is some water two or three steps in front of him, he can drink the water while performing prayers. However, he must not do anything that invalidates prayers, such as turning away from qibla.