“The sun and the moon follow a precise reckoning.”

And the Most High says:

“He causes the dawn to break, and has made the night for rest, and the sun and the moon for reckoning. That is the determination of the Almighty, the All-Knowing.”

And the Most High says:

“They ask you about the crescent moons. Say, ‘They mark appointed times for people and for Hajj.’”

And the Most High says:

“Indeed, the number of months with Allah is twelve, as ordained in Allah’s Record on the day He created the heavens and the earth; four of them are sacred. That is the upright religion.”

And the Most High says:

“And a sign for them is the night: We strip the daylight from it, and suddenly they are in darkness.”

“And the sun runs towards its appointed resting place. That is the determination of the Almighty, the All-Knowing.”

“And the moon—We have determined phases for it until it returns like an old date stalk.”

“It is not for the sun to overtake the moon, nor does the night outstrip the day. Each floats in an orbit.”

Just as Allah Most High has established the regular order whereby the crescent moon first appears only on the thirtieth or thirty-first night of the month, and a month consists only of thirty or twenty-nine days—so that anyone who supposes a month can be longer or shorter is mistaken—likewise, Allah has established the regular order whereby a solar eclipse occurs only when the moon is hidden from view, and a lunar eclipse occurs only when the moon is full. The full moon occurs on the bright nights whose days it is recommended to fast: the thirteenth, fourteenth and fifteenth nights. A lunar eclipse occurs only on these nights.