Sahih Al Bukhari – Book of Prayers (Salat)

Volumn 001, Book 008, Hadith Number 441.
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Narated By 'Ubdaidullah Al-Khaulani : I heard 'Uthman bin 'Affan saying, when people argued too much about his intention to reconstruct the mosque of Allah's Apostle, "You have talked too much. I heard the Prophet saying, 'Whoever built a mosque, (Bukair thought that 'Asim, another subnarrator, added, "Intending Allah's Pleasure"), Allah would build for him a similar place in Paradise.'"