It is narrated from Sayyiduna Abu Qatadah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) delivered a sermon in which he mentioned jihad, and he did not declare anything superior to it except the obligatory (prayer). This is evidence that jihad is a communal obligation (fard kifayah), since it was placed a degree below the individual obligation.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب السير / 17944