Activists have circulated photos on the Internet of killed Tawhid Brigade commander Abdelkader Saleh, who was killed in Aleppo last week.
The pictures are the first images to appear since his assassination.
The key rebel Islamic movement was cleared of any doubts or quesrtions over his death.
Saleh was buried in his hometown, Marea, with no funeral ceremony, according to a Zaman al-Wasl source.
The prominent military commander died of his wounds in a Turkish hospital after two days of coming under an attack by Assad airstrikes, along with top rebel leaders in Aleppo last week, in a setback to rebels defending the city.
Aleppo was Syria's commercial hub and the most populous city before the uprising against Assad erupted in 2011, and has been witnessing heavy fighting since Assad's forces, backed by Shiite militia from Iraq and the Lebanese party Hezbollah, launched an offensive two weeks ago to retake rebel-held areas in the city, according to Reuters.
The opposition Aleppo News Network said Friday in a statement that the raid on Thursday targeted an army base that rebels had captured, killing commander Youssef al-Abbas of the Tawhid Brigades, one of the biggest armed opposition groups.
Tawhid's leadership was holding a meeting in the base when the raid occurred, the statement said.
Saleh was taken to a hospital in Turkey, 45 kms to the north, along with Abdelaziz al-Salameh, another top commander, the statement said.
Translated and edited by The Syrian Observer