Does concealing financial expenditure in the path of Allah, His Messenger, and the believers make it greater in reward and recompense from Allah, based on His saying, the Almighty: "And say, 'Do [as you will], for Allah will see your deeds, and [so will] His Messenger and the believers'"?

Concealing charity is better than declaring it, as it is closer to sincerity and further from showing off, and less embarrassing for the poor. However, obligatory Zakat is an exception; declaring it is better because it is a ritual and a pillar of Islam. The aforementioned verse contains encouragement, deterrence, promise, and warning, and it came in the context of discussing hypocrites. It also states that Allah will recompense both the good-doer and the evil-doer for their deeds.