Millions of Muslims across the globe are celebrating Eid al-Adha on Tuesday, marking the end of the annual Hajj pilgrimage. The holiday is also an Islamic religious festival commemorating Prophet Abraham's faithfulness to God after being tested with the unfulfilled command to sacrifice his son. Eid al-Adha is a three-day celebration in Muslim-majority countries. In the United States, most people observe just one day. 📸: @apnews, @GettyImages, AFP via @ #EidMubarak #EidAlAdha