Is it permissible to pray while needing to use the toilet?

Prayer should be performed with humility and a sense of being in the presence of Allah. Therefore, it is important to eliminate as much as possible any situations that may distract attention during prayer. For example, unless the prayer time is about to end, it is not considered appropriate for a hungry person to start praying while food is ready. The need to use the toilet also disrupts humility and concentration in prayer, so it is disliked (makruh) to pray in such a state. The Prophet Muhammad (s.a.s.) stated that the prayer of a person who is holding back urine or who prays while food is ready will not have its full merit. (Muslim, Masajid, 67 [560])

Source: T.C. Diyanet İşleri Başkanlığı, Din İşleri Yüksek Kurulu