The fourth Imam, Imam Sajjad (a.s.), recited a prayer in the first day or the first night of Ramadan. In a part of this prayer in the Al-Sahifa al-Sajjadiyya this statement was told:
"Praise to GOD who is the most capable who has set his month, Ramadan, the month of fasting, the month of Islam, as one of the ways of beneficence."
He has named Ramadan the month of GOD, because it is the month of obeisance, servitude and expanding them or the sense is the Islam religion because the obligation of fasting is the characteristic of the Islamic nation and Muslims.
Welcoming Ramadan the holy prophet has said to the Muslims:
"GOD has specified you to Ramadan" (1)
And Imam Sadiq (a.s.) has said that: "Islam was based on prayer, Zakat, Hajj, Fasting, Leadership and in Islam nothing was argued in the level of Leadership." (2)