Isaac of Nineveh

One who passes the night with thought of him makes of God a housemate; and one who earnestly desires the will of God will find the watchers on high to be his teachers.

[God] showed that His true servants and friends are those who walk before Him in fear and reverence and do His will, since virtuous deeds and purity of conscience are things holy [and beloved] of God. But when people repudiate His paths, the Lord repudiates them, casts them away from His face and takes from them His grace. For why was the sentence against Baltasar issued so swiftly and why did it strike him down, as it were, by the form of a hand? Was it not because he acted with audacity toward the untouchable vessels of offering he seized from Jerusalem, drinking out of them, both he and his concubines? In the same manner, those who have consecrated their members to God but are so audacious as to use them once more for worldly deeds, the same perish, being smitten by an invisible blow.