Sunan Abi Dawud Book 2, Hadith 69
It was said that when a man removed gravels from the mosque, they adjured him.
I asked Ibn 'Umar about the gravel spread pin the mosque. He replied: One night the rain fell and the earth was moistened. A man was bringing the gravel (broken stones) in his cloth and spreading it beneath him. When the Messenger of Allah (ﷺ) finished his prayer, he said: How fine it is !
The gravels adjure the person when removes them from the mosque.