Knowing the Greatness of the Reward for Weeping, Especially When One is Alone
It was narrated that Abu Hurayrah (may Allaah be pleased with him) said: The Messenger of Allaah (صلى الله عليه وسلم) said: “A man who weeps for fear of Allaah will not enter Hell until the milk goes back into the udder, and dust produced (when fighting) for the sake of Allaah and the smoke of Hell will never coexist.” [Narrated by al-Tirmidhi, 1633; al-Nasaa’i, 3108; classed as saheeh by al-Albaani]. “Until the milk goes back into the udder” is a metaphor for it being impossible, as in the verse where Allaah says (interpretation of the meaning): “and they will not enter Paradise until the camel goes through the eye of the needle” [al-A’raaf 7:40].
Tuhfat al-Ahwadhi. And it was narrated that he said: The Messenger of Allaah (صلى الله عليه وسلم) said: “There are seven whom Allaah will shade with His shade on the day when there will be no shade but His: a just ruler; a young man who grows up worshipping Allaah; a man whose heart is attached to the mosque; two men who love one another for the sake of Allaah, meeting and parting on that basis; a man who is called (to commit sin) by a woman of high status and great beauty and he says, ‘I fear Allaah’; a man who gives in charity so secretly that his left hand does not know what his right hand is doing; and a man who remembers Allaah when he is alone and his eyes flow with tears.” Narrated by al-Bukhaari, 660; Muslim, 1031.
Weeping when alone is singled out because being alone is a time when the heart tends to become harder and there is a stronger motive to commit sin, and it is farthest removed from the possibility of showing off.
So if a person strives to do this, and makes himself feel the greatness and might of Allaah, and his eyes flow with tears, then he deserves to be beneath the shade of the Throne of the Most Merciful on the Day when there will be no shade but His shade.