ٱتَّخَذُوٓا۟ أَيْمَـٰنَهُمْ جُنَّةً فَصَدُّوا۟ عَن سَبِيلِ ٱللَّهِ فَلَهُمْ عَذَابٌ مُّهِينٌ
Ittakhazooo aymaanahum junnatan fasaddoo 'an sabeelil laahi falahum 'azaabum muheen
They have taken their oaths as a shield and turned others away from the path of God, so a humiliating punishment awaits them.
Junna is a shield, from a root that runs through concealment: the jinn who are hidden, the garden covered over by its own foliage. The oath here works as cover, sworn to protect standing in the community rather than to bind the one swearing. The punishment named is muhīn, humiliating, which answers exactly what the shield was raised to protect.