Full Sharh — Mishkat al-Masabih 662
وَعَنْ أَبِي هُرَيْرَةَ قَالَ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: «إِذَا قَامَ أَحَدُكُمْ إِلَى الصَّلَاةِ فَلَا يَبْصُقْ أَمَامَهُ فَإِنَّمَا يُنَاجِي اللَّهَ مَا دَامَ فِي مُصَلَّاهُ وَلَا عَنْ يَمِينِهِ فَإِنَّ عَنْ يَمِينِهِ مَلَكًا وَلْيَبْصُقْ عَنْ يَسَارِهِ أَوْ تَحْتَ قَدَمِهِ فَيَدْفِنُهَا» وَفِي رِوَايَةِ أَبِي سَعِيدٍ: «تَحْتَ قدمه الْيُسْرَى»
English Translation
Abu Huraira reported God’s Messenger as saying, “When one of you gets up for prayer he must not spit in front, of him, because he is holding intimate converse with God as long as he is in his place of prayer; nor must he spit towards his right, for there is an angel at his right; but he may spit towards his left or under his feet and bury it.” The version of Abu Sa'id has “under his left foot.” (Bukhari and Muslim.)
Source
Mishkat al-Masabih(مشكاة المصابيح)
Prayer
Hadith Number
662