Prophet Yahya (peace be upon him) once came to Bayt al-Maqdas and witnessed some clerics and priests wearing coarse garments and woolen caps. He requested his mother to arrange for him a similar dress so that he too could engage himself in worship with them. When his mother gave him the outfit, he engaged himself in worship in Bayt al-Maqdas.
One day, looking at himself in the mirror and observing that he had become very thin, he began to weep. God revealed to him: You weep because your body has become thin? By My Honour and Glory! If you were to possess the slightest awareness of the fire of Hell, you would have worn a garment made of iron rather than one made of fabric. Hearing this, Yahya (peace be upon him) wept immensely and intensely.
One day his father, Zakariya (peace be upon him) said to him: Dear son! Why do you weep so much? I had sought you from God so that you may be the apple of my eye!
Yahya (peace be upon him) replied: But were you not the one, who had said that between Paradise and Hell lies a pass; none shall traverse it except those who weep intensely out of fear of God?
Yahya (peace be upon him) used to weep so much that his mother arranged for him two pieces of felt, which would absorb the tears which flowed from his eyes. When they would become drenched with his tears, he would squeeze the felt and tears would flow down from them from between his fingers.
Zakariya (peace be upon him) would look at his son, raise his head towards the heavens and say: O’ Lord! This is my son and these are his tears and You are the most Merciful of the merciful ones.
When Yahya (peace be upon him) would hear the name of Sukran (a mountain in Hell), in a state of utter perturbation and distress, he would rush out into the desert crying: Woe (unto me) due to heedlessness (with respect to God), and his father and mother would rush out after him in the desert.( Risaalah Liqaa Allah, pg. 157; Amaali Al-Saduq. )