It is narrated from Sayyiduna Ibn Abbas (may Allah be pleased with them both) that the Messenger of Allah (peace and blessings be upon him) said: "Whoever among you is unable to wage jihad against the enemy, and unable to strive in worship at night, let him remember Allah abundantly."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 11075