We were in the company of 'Aishah. When her food was brought in, al-Qasim stood up to say his prayer. Thereupon , 'Aishah said : I heard the Messenger of Allaah (sal Allaahu alayhi wa sallam) say: Prayer should not be offered in presence of meals, nor at the moment when one is struggling with two evils (e.g. when one is feeling the call of nature.)  

كُنَّا عِنْدَ عَائِشَةَ فَجِيءَ بِطَعَامِهَا فَقَامَ الْقَاسِمُ يُصَلِّي فَقَالَتْ سَمِعْتُ رَسُولَ اللَّهِ ﷺ يَقُولُ لاَ يُصَلَّى بِحَضْرَةِ الطَّعَامِ وَلاَ وَهُوَ يُدَافِعُهُ الأَخْبَثَانِ