This sadness will continue until the journey through the intermediate world of the grave is completed, safe and sound, and the believer flies to the abode of eternal happiness and blessing without being detained by the Supreme Tribunal in the Hereafter. A believer's sorrows will never stop until the meaning of: Praise be to God, Who has put grief away from us. Surely our Lord is All-Forgiving, Bountiful (35:34) becomes manifest.
Sorrow or sadness arises from an individual's perception of what it means to be human, and grows in proportion to the degree of insight and discernment possessed by one who is conscious of his or her humanity. It is a necessary, significant dynamic that causes a believer to turn constantly to the Almighty and, perceiving the realities that cause sadness, seek refuge in Him and appeal to Him for help whenever he or she is helpless.
A believer aspires to very precious and valuable things, such as God's pleasure and eternal happiness, and therefore seeks to do a "very profitable business" with limited means in a short span of time (his or her life). The sorrows a believer experiences due to illness and pain, as well as various afflictions and misfortunes, resemble an effective medicine that wipes away one's sins and enables the eternalization of what is temporary, as well as the expansion of one's "droplike" merit into an ocean. It can be said that a believer whose life has been spent in continuous sadness resembles, to a certain degree, the Prophets, for they also spent their lives in this state. How meaningful it is that the glory of mankind, upon him be peace and blessings, who spent his life in sorrow, is rightly described as the Prophet of Sorrow by Necib Fazil, the famous Turkish poet and writer.
Sadness protects a believer's heart and feelings from rust and decay, and compels him or her to concentrate on the inner world and how to make progress along the way. It helps the traveler on the path of perfection to attain the rank of a pure spiritual life that another traveler cannot attain through several forty-day periods of penitence and austerity. The Almighty considers hearts, not outward appearances or forms. Among hearts, He considers the sad and broken ones and honors their owners with His presence, as stated in a narration: I am near those with broken hearts. 
Sufyan ibn Uyayna says: God sometimes has mercy on a whole nation because of the weeping of a sad, broken-hearted one.  This is so because sorrow arises in a sincere heart, and among the acts making one near to God, sadness or sorrow is the least vulnerable to being clouded by ostentation or one's desire to be praised. Part of every bounty and blessing of God is assigned to those who need it to purify that bounty or blessing of certain impurities. That part is called zakat, which literally means "to cleanse" or "to increase," for it cleanses one's property of those impurities that entered it while it was being earned or used, and causes it to increase as a blessing of God. Sadness or sorrow fulfills a similar role, for it is like the part in one's mind or conscience that purifies and then maintains their purity and cleanliness.
It is narrated in the Torah that when God loves His servant, He fills his or her heart with the feeling of weeping; if He dislikes and gets angry with another, He fills his or her heart with a desire for amusement and play. Bishr al-Khafi says: Sadness or sorrow is like a ruler. When it settles in a place, it does not allow others to reside there.  A country with no ruler is in a state of confusion and disorder; a heart feeling no sorrow is ruined.
Was the one with the most sound and prosperous heart, upon him be peace and blessings, not always sad-looking and deep in thought? Prophet Jacob, upon him be peace, "climbed and went beyond the mountains" between him and his beloved son, Prophet Joseph, upon him be peace, on the wings of sorrow and witnessed the realization of a pleasing dream. The sighs of a sorrowful heart are regarded as having the same value and merit as the habitual recitations and remembrance of those who regularly and frequently worship God, and the devotion and piety of ascetics who abstain from sin.
The truthful and confirmed one, upon him be peace and blessings, says that grief arising from worldly misfortune causes sins to be forgiven.  Based on this statement, one can see how valuable and meritorious are the sorrows arising from one's sins, from the fear and love of God, and pertaining to the Hereafter. Some feel sorrow because they do not perform their duties of worship as perfectly as they should. They are ordinary believers. Others, who are among the distinguished, are sad because they are drawn toward that which is other than God. Still others feel sad because, while they feel themselves to be always in God's presence and never forget Him, they also are [spending time] among people in order to guide them to the Truth. They tremble with fear that they may upset the balance between always being with God and being in the company of people. These are the purified ones who are responsible for guiding the people.
The first Prophet, Adam, upon him be peace, was the father of humanity and Prophets, and also the father of sorrow. He began his worldly life with sorrow: the fall from Paradise, Paradise lost, separation from God, and, thereafter, the heavy responsibility of Prophethood. He sighed with sorrow throughout his life. Prophet Noah, upon him be peace, found himself enveloped by sorrow when he became a Prophet. The waves of sorrow coming from the absolute unbelief of his people and their impending chastisement by God appeared in his chest as the waves of oceans. A day came, and those waves caused oceans to swell so high that they covered mountains and caused the earth to sink in grief. Prophet Noah became the Prophet of the Flood.
Prophet Abraham, upon him be peace, was as though programmed according to sorrow: sorrow arising from his struggle with Nimrod, being thrown into fire and living always surrounded by "fires," leaving his wife and son in a desolate valley, being ordered to sacrifice his son, and many other sacred sorrows pertaining to the inner dimensions of reality and meanings of events. All of the other Prophets, such as Moses, David, Solomon, Zachariah, John the Baptist, and Jesus, upon them be peace, experienced life as a series or assemblage of sorrows, and lived it enveloped with sorrow. The Greatest of the Prophets and his followers tasted the greatest sorrows.
 Kushayri, el-Risala al-Quashayriya, p.139.
 Quashayri,ibid., p.138.
 Haythami, Majma' al-Zawa'id, 4.63.