Hadhrat Umar (radhiyallahu anhu), the Second Khalifah of Rasulullah (sallallahu alayhi wasallam) was on his way to take possession of the conquered city of Jerusalem. Along the journey he stopped at a place called Jaabiyah where he addressed the Muslims.
The following are some excerpts from his Khutbah of admonition delivered on this occasion:
"O People! Reform your innerselves (souls), then your outer-selves (worldly affairs) will be rectified (automatically). Practise (righteousness) for your Aakhirah, then your worldly affairs will be seen to ....... Whoever intends to take the direction of the Path of Jannat should hold on to the Jama'ah (i.e. Ahlus Sunnah wal Jama'ah). Verily shaitaan is with the lone person. He remains far from two persons. Never any of you be alone with a woman, for verily, the third one present is shaitaan. He who derives happiness from his virtuous deeds and is grieved by his evil deeds, verily, he is a Mu 'min."