Muhammad bin Zayd bin 'Abdullah محمد بن زيد بن عبد الله بن عمر · The Book on Virtues of Jihad

That the Messenger of Allah (ﷺ) said: "Whoever spends a sum in the cause of Allah, it is recorded for him seven-hundred fold." 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)