President Barack Obama has sent his greetings to Muslims around the world for Ramadan, the holiest month on the Islamic calendar.

In a statement Monday, the president said Ramadan is a time for deep reflection and sacrifice, and that it also draws families and communities together for prayers and iftars — shared meals that break the daybreak-to-sunset fast.

Mr. Obama wished Muslims a “blessed month” and said he looks forward to hosting an iftar dinner at the White House.

The president said Ramadan is also a reminder of the importance of reaching out to the less fortunate, noting the “heartbreaking accounts” of deaths and the images of families and children in Somalia and the Horn of Africa struggling to survive. He called on nations and peoples to come together to support aid efforts to avert an even worse catastrophe.

Ramadan is the ninth month of the Islamic lunar calendar. The start of the holiday is determined by the appearance of the new moon.

During Ramadan, Muslims are expected to fast and abstain from smoking and sex from dawn to sunset. The month ends with a celebration called Eid al-Fitr.