The reward for establishing a Masjid is truly immense, Allaah’s Messenger (may the peace and salutations of Allaah be upon him) said:
“Whoever builds a Mosque for the sake of Allaah, Allaah will build for him a house in Paradise.” (Reported by Bukhaaree and Muslim).
On an occasion, the noble Companion, Uthmaan (may Allaah be pleased with him) addressed his companions saying:
“I ask you by Allaah and Islaam! Do you know that the Mosque of the Prophet (may the peace and salutations of Allaah be upon him) was too small for its people, so the Messenger of Allaah (may the peace and salutations of Allaah be upon him) said: ‘Who will purchase the land of the family of so-and-so and add it to this Mosque in exchange for better than that in Paradise?’ So I bought it with the core of of my wealth and presented it to the Messenger.” (Reported authentically by at-Tirmidhee, no. 3703)
Allaah, the Mighty and Majestic, has stated:
“Spend from what we have provided you before death approaches one of you and he says, ‘My Lord, if only you would delay me for a brief term so I would give charity and be among the righteous.’”
Qur’aan 63:10
A man asked the Prophet (may the peace and blessings of Allaah be upon him): “Which charity brings the greatest reward?” He replied:
“That you give in charity when you are healthy, feeling miserly, whilst you fear poverty and are in hope of becoming rich. So do not delay until you are at the point of death and then you say: “Give this to so-and-so and give that to so-and-so,” when at that point [your wealth and property] already belongs to so-and-so!” (Al-Bukhaaree, no. 1419)