The inner and outer Temple

Whoever built a mosque, (intending Allah's pleasure),
Allah would build for him a similar place in Paradise.

Hadith, Sahih Bukhari - Volume 1

He who treads the path in search of knowledge,
Allah will make that path easy,
leading to Paradise for him and those persons
who assemble in one of the houses of Allah (mosques),
recite the Book of Allah and learn
and teach the Qur'an (among themselves).
There will descend upon them tranquillity,
mercy will cover them, the angels will surround them
and Allah will mention them in the presence of those near Him.

Hadith, Sahih Muslim, Book 34

There is a mosque whose foundation
was laid from the first day on piety;
it is more worthy of the standing forth (for prayer) therein.
In it are men who love to be purified;
and Allah loveth those who make themselves pure.
Which then is best?
- he that layeth his foundation on piety
to Allah and His good pleasure?
- or he that layeth his foundation on an undermined sand-cliff
ready to crumble to pieces?
and it doth crumble to pieces with him, into the fire of Hell.
And Allah guideth not people that do wrong.
The foundation of those who so build
is never free from suspicion and shakiness in their hearts,
until their hearts are cut to pieces.
And Allah is All-Knowing, Wise.

Qur'an, Sure 9,108-110