The Prophet scratched some spittle from the prayer direction of the mosque.
Sunan Ibn Majah Book 4, Hadith 30
← Previous Hadith "The Messenger of Allah saw some sputum in the prayer direction of the mosque, when he was praying in front of the people. He scratched it off, then when the prayer was over, he said: 'When anyone of you is performing prayer, Allah is before him, so none of you should spit toward the front while praying.'"

Sunan Ibn Majah Book 4, Hadith 29 Next Hadith → "The Messenger of Allah performed prayer, then a man said: 'Who was looking for the red camel?' The Prophet said: 'May you not find it! The mosques were built for that for which they were built.'"

Sunan Ibn Majah Book 4, Hadith 31