They are a tribe from the Children of Israel who believed in him, and they supported him.
(When Jesus sensed disbelief from his people, he asked, “Who will stand up with me for Allah?” The disciples replied, “We will stand up for Allah. We believe in Allah, so bear witness that we have submitted.”) Al-Imran 3:52
طائفة من بني إسرائيل آمنوا بعيسى عليه السلام ووازروه ونصروه
(فَلَمَّا أَحَسَّ عِيسَىٰ مِنْهُمُ الْكُفْرَ قَالَ مَنْ أَنصَارِي إِلَى اللَّـهِ ۖ قَالَ الْحَوَارِيُّونَ نَحْنُ أَنصَارُ اللَّـهِ آمَنَّا بِاللَّـهِ وَاشْهَدْ بِأَنَّا مُسْلِمُونَ ﴿٥٢ )
52 : 3 أل عمران