They ask you (O Muhammad SAW) about the new moons. Say: These are signs to mark fixed periods of time for mankind and for the pilgrimage. It is not Al-Birr (piety, righteousness, etc.) that you enter the houses from the back but Al-Birr (is the quality of the one) who fears Allah. So enter houses through their proper doors, and fear Allah that you may be successful." (2:189)

It is He Who made the sun a shining thing and the moon as a light and measured out its (their) stages, that you might know the number of years and the reckoning. Allah did not create this but in truth. He explains the Ayat (proofs, evidences, verses, lessons, signs, revelations, etc.) in detail for people who have knowledge." (10:5)