Sahih al-Bukhari 532
Sahih al-Bukhari · Book 9: Times of the Prayers · A person in Salat (prayer) is speaking in private to his Lord (Allah)
Narrated Anas:
حَدَّثَنَا حَفْصُ بْنُ عُمَرَ ، قَالَ حَدَّثَنَا يَزِيدُ بْنُ إِبْرَاهِيمَ ، قَالَ حَدَّثَنَا قَتَادَةُ ، عَنْ أَنَسٍ ، عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ " اعْتَدِلُوا فِي السُّجُودِ، وَلاَ يَبْسُطْ ذِرَاعَيْهِ كَالْكَلْبِ، وَإِذَا بَزَقَ فَلاَ يَبْزُقَنَّ بَيْنَ يَدَيْهِ وَلاَ عَنْ يَمِينِهِ، فَإِنَّهُ يُنَاجِي رَبَّهُ " .
The Prophet (ﷺ) said, "Do the prostration properly and do not put your forearms flat with elbows touching the ground like a dog. And if you want to spit, do not spit in front, nor to the right for the person in prayer is speaking in private to his Lord."