Four Boundaries

Imam Ibn Qayyim al-Jawziyah (may Allah have mercy on him) said:

It was said: “The one who keeps the four boundaries, he will save his religion, and these are the moments (of the sight), the train of thought, words and steps.” Therefore, the slave should be his own guard at these four gates, and be vigilant, guarding these borders, since from there an enemy can penetrate to him, who will prowl among the dwellings in search of everything sublime in order to destroy him. Most disobediences enter the slave through these four doors.

 See Jawab al-Kafi.