Sayings of Iman Ali a.s about the holy month of Ramadan:

Imam Ali (as) said:

"It is incumbent upon you to seek forgiveness and
supplicate excessively in the month of Ramadhan.
As for the supplication, by means of it the
calamities are warded off from you, and as for
the seeking of forgiveness, it erases away your
sins."

Al-Kafi, vol. 4, pg. 88