Abu Huraira (may Allah be pleased with him) narrates that the Messenger of Allah (peace and blessings be upon him) said: If I did not consider it difficult for my Ummah (or people), I would not like to stay behind any army that sets out for Jihad in the way of Allah. But neither do I have the means of conveyance, nor do they have enough means to accompany me, and it is also unpleasant for them to stay behind me. I wish that I be martyred fighting in the way of Allah, then brought back to life, then martyred again, then brought back to life, then martyred again.
Hadith Referenceالمنتقى ابن الجارود / كتاب الطلاق / 1033