Abdullah bin Umar reported,

The Messenger of Allah ﷺ saw some phlegm on the wall facing the qiblah, so he took a stick or a pebble and scraped it off. Then he said, "When one of you stands to pray, let him not spit toward his qiblah, for he is conversing privately with his Lord ."

حدثنا يزيد أخبرنا محمد عن نافع

عن ابن عمر قال

رأى رسول الله ﷺ في القبلة نخامة فأخذ عودا أو حصاة فحكها به ثم قال إذا قام أحدكم يصلي فلا يبصق في قبلته فإنما يناجي ربه تبارك وتعالى