Sayyiduna Ubadah bin al-Samit (may Allah be pleased with him) said that the Messenger of Allah (peace and blessings be upon him) said: "Hold fast to jihad in the path of Allah, for it is one of the gates of Paradise, and through it Allah Almighty removes grief and sorrow." Others besides him added these words: "And strive in the path of Allah against the near and the far, establish the limits (hudud) of Allah upon the near and the far, and do not fear, in the religion of Allah, the blame of any blamer."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب السير / 17799