Al-Adab Al-Mufrad, Hadith 455 ⓘ
He continued, "Then we came to him another time while he was building a wall and his and he said, 'The Muslim is rewarded for everything on which he spends money except for what he spends on dust.'
ثُمَّ أَتَيْنَاهُ مَرَّةً أُخْرَى، وَهُوَ يَبْنِي حَائِطًا لَهُ، فَقَالَ: إِنَّ الْمُسْلِمَ يُؤْجَرُ فِي كُلِّ شَيْءٍ يُنْفِقُهُ إِلاَّ فِي شَيْءٍ يَجْعَلُهُ فِي التُّرَابِ.
also referenced under: Book 25, Hadith 14 (In-Book) & Book 25, Hadith 455 (English)