In Gulf Arab states, men often wear a traditional white robe called a thobe for Eid al-Fitr.
A thobe, also spelled thawb or thob, is a long-sleeved, ankle-length garment worn across the Arabian Peninsula. The same basic clothing tradition has regional names: it is often called a dishdashah in Kuwait and Oman, and a kandura in the United Arab Emirates. White is especially common in the hot season because the color reflects sunlight, while heavier or darker versions may appear in cooler weather.
The garment is everyday clothing in much of the Gulf, but Eid gives families a reason to buy a new one or wear their finest version. Men may pair it with a ghutrah, a square head covering held in place by an agal. On especially formal occasions, including religious holidays, some men add a bisht, a flowing cloak often trimmed with decorative braid.
A common mix-up is confusing the thobe with the bisht: the thobe is the ankle-length robe itself, while the bisht is an outer cloak worn over it. Spelling varies, but “thobe” is a fair English answer.