Narrated Khuraim bin Fatik:
That the Messenger of Allah (ﷺ) said: Whoever spends a sum in the cause of Allah, it is recorded for him seven-hundred fold.
[Abu 'Eisa said:] There are something on this topic from Abu Hurairah.
This Hadith is Hasan, we only know of it from the narration of Ar-Rukain bin Ar-Rabi' (a narrator in the chain of this Hadith)