“The Mosques of Allah shall be maintained only by those who believe in Allah and the Last Day. They perform Salah (prayer), and give Zakat (charity) and fear none but Allah. It is they who are expected to be on true guidance.”
[at-Tawbah 9:18]
Jaabir ibn ‘Abdullah (may Allah be pleased with him) that the Messenger of Allah (blessings and peace of Allah be upon him) said:
“Whoever builds a mosque for the sake of Allah, like a sparrow’s nest or even smaller, Allah will build for him a house in Paradise.”
[Ibn Maajah]
This hadeeth is encouraging everyone to contribute to the building of Mosques, even if it is a small amount.
Finally, the one who participates in or contributes to building a mosque will have a reward commensurate with his contribution