Sahih al-Bukhari 753
صحيح البخاري#753SahihNarrated Ibn `Umar:The Prophet (ﷺ) saw expectoration in the direction of the Qibla of the mosque while he was leading the prayer, and scratched it off. After finishing the prayer, he said, "Whenever any of you is in prayer he should know that Allah is in front of him. So none should spit in front of him in the prayer
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Every narration in Sahih al-Bukhari is accepted as Sahih (authentic) by the established status of the book.
In-book reference: 10:147