A person who knows his Lord should constantly be in the service of his Lord, because he recognises and appreciates the value and importance of time; therefore during the day he observes his duties and fulfils the rights of the King [Allah], while his night is dedicated to conveying his love and devotion to his Lord; thus he never finds a moment of repose.
When the perceptive heart ponders the consequences of actions, just as how Yusuf, peace be upon him, did when he was seduced, it cuts off the hands of the covetous self with the knife of longing to his Lord. For them, a camel entering through the eye of needle would be easier than having to hear reproach or criticism with respect to their worship. And when the time comes [i.e. the Day of Judgement] those who travelled throughout the night [i.e. worshipping] will rejoice for traversing the long miles [towards the Hereafter] and the tongue of their endeavours will rebut the approach, “This is he on whose account you blamed me” (Yusuf 12:32) Indeed, the more endeavours and aspirations magnify, the less significant the corporeal body becomes.
Yahya ibn Muadh said: “Let solitude be your abode and beseeching your Lord be your speech; either you die from your illness or you procure its remedy eventually. Some people entered upon Abu Bakr al-Nahshali, a pious preacher, while he was in the market, and they found him bowing and prostrating even there. Some people entered upon al-Junayd while he was on his deathbed, and they found him praying. After he finished, they greeted him and so he replied to their greeting and said: This is not a time for wasting, after which he commenced the Salah again.
Their hearts quake out of their fear of Allah, just as a bouncing ball wobbles when hit with a stick. Thus, their hearts held in pass of anxiety are carried into the vast lands of love, where you find the passionate being overwhelmed while invoking his Lord, the tranquil supplicating freely and the fearful seeking the refuge with his Lord.
Their bodies, once in their prime, have worn our due to their self-discipline; their souls have been bejewelled inside the shell of body; and so both take upon the quest of yearning for their Lord. Their tongues are busy in the remembrance of Allah, their inner thoughts are overwhelmed by Allah’s love, their eyes shed tears of fear, and their self flees from this life to the house of asceticism.
Whenever people saw al-Hasan al-Basri, they would think as though calamity had just fallen him. Malik ibn Dinar had a black line running down his cheek from how much his eyes shelters. Ata al-Salami used to weep in his room so much that his tears would drain into the gutter of his house; one day his tears splashed on a person who was walking in the street, whereupon the man shouted; O people of the house, is the water pure? Ata replied: You should wash it off because these are the tears of a person who had disobeyed Allah. And when Dawud, peace be upon him, was brought a half-full vessel he would drink from it until he filled the remaining part of the vessel with his tears.
Seeds of Admonishment and Reform by Imam Ibn Jawzi Pages 182-184