He has urged Muslims to pray for the safety, progress and prosperity of Ghana.
Mahama in a Facebook post said: "With the start of the 2019 holy month of Ramadan, I wish to extend my warmest felicitations to our Muslim brothers and sisters as they begin the 30-day fast.
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"Ramadan is a month of self-denial, dedication to the will of Allah and personal spiritual and moral growth for all who go through the ritual of the fast. Ramadan is a month of peace and love. Let this be manifest in our lives in this holy month and beyond.
"As you go through this period of Ramadan, I urge our Muslim brothers and sisters to offer supplications to Allah for the safety, progress and prosperity of our dear nation.
"Ramadan Kareem!"
Muslims in Ghana will from today join other Muslims worldwide for Ramadan after it was confirmed that the moon has been seen.
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Muslims, during this Ramadan period, are expected to fast from dawn to dusk, for about 28 to 29 days.
During this time they are expected to spend more time in prayers and the study of the Quran.