Bitter hatred and animosity aren’t stopping Shiite Lebanese farmers from selling weed to their sworn enemies — Sunni Islamic State militants — because, well, that’s business.

The Daily Beast spoke with farmers in Lebanon’s Bekaa Valley, supporters of the embattled Bashar al-Assad regime in Syria, who are selling marijuana to Islamic State militants.

Lebanese Shiites typically support Syria’s Assad as a longtime regional ally, and the Islamic State, controlling territory in Syria and Iraq, are staunch enemies of the regime. Additionally, in Iraq, the Islamic State is fighting Iran-backed Shiite militias.

One source who spoke to The Daily Beast said he sold a ton of hash to Islamic State recruits just last month. According to Daily Beast contributor Jesse Rosenfeld, the exchange also included “some coke and pills.”

But the 50 year-old farmer once fought with Hezbollah, a Shiite Lebanese terror organization, against the Islamic State in Syria. And Islamic State jihadis beheaded one of his relatives in the northeastern Lebanese town...