The first thing Prophet Muhammad (pbuh) has done on entering Median is that he built a mosque, a deed considered of the most virtuous deeds. Mosques are the best places on earth and the dearest to Allah Almighty, as the Prophet (pbuh) said: (the dearest places to Allah are mosques, and the most detested places t o Allah are markets), related by Muslim.

Accordingly, Almighty Allah held great reward for those constructing mosques, where the Prophet said: (Who builds a mosque for Allah; then Allah will build likewise for him in paradise). Muslim

One my say that constructing mosques needs a lot of money which is attained only by the rich, however, the Prophet  gives glad tidings for Muslims as saying: (who builds a mosque for Allah even if it is like or smaller than the nest of the sand grouse, then Allah will build for him a house in paradise). Ibn Majah

Since there is no mosque as small as the nest of the sand grouse, then it would manifestly denote that this reward is attained by participating in constructing a big mosque even by share equal to the sand grouse nest, namely paying little money.

Now, door is open for all of us and not only limited to the rich of Muslims, and this is indeed the grandeur of this religion.