The Meaning of Waning
Futur linguistically: is brokenness and weakness. It is said: fatara yafturu futuran wa futaran if one becomes still after being sharp, and soft after being intense.  See: Lisan al-`Arab Ibn Manzur (5/43); Taj al-`Arus, al-Zabidi (13/293).
Futur technically: is laziness, lethargy, and slowing down after having been serious, invigorated, and lively.  See: al-Futur al-Mazahir al-Asbab al-`Ilaj, Nasir al-`Umar (p. 22). Dispraise of Waning in the Qur’an and Sunnah
❖ Allah, exalted, said: “They glorify Him day and night, never waning.” al-Anbiya’: 20. Meaning, they do not wane or bore.  Ghara’ib al-Qur’an, al-Nisapuri (5/9).
❖ Allah, exalted, said about Musa, peace be upon him: “Go, you and your brother, with My signs and do not slacken taniya - to do wana in My remembrance. Go, both of you, to Pharaoh. Indeed, he has transgressed.” Ta Ha: 42 - 43. Wana here is waning and falling short.  al-Kashshaf, al-Zamakhshari (3/65).
❖ `A’ishah, Allah be pleased with her, narrated that the Messenger of Allah ﷺ used to seek refuge, saying: “Allah, I seek refuge in you from laziness, weak old age, sinful acts, and demeaning debts.”  Reported by al-Bukhari (6368) and the wording is his, as well as Muslim (589). Quotes of the Predecessors and Scholars on Waning
❖ `Umar ibn al-Khattab said: “Adulation causes waning and begets arrogance and vanity.”  Mentioned by al-Ghazali in Ihya’ `Ulum al-Din (3/160).
❖ Ibn Mas`ud said: “Do not try to overpower the night, for you will not be able to withstand it. If one of you feels the need to sleep, let him go to bed. That is more sound for him”  Reported by `Abd al-Razzaq in al-Musannaf (4223), Ibn Abi Shaybah in al-Musannaf (35708), and al-Tabarani (9/110) (8554), and the wording is his. al-Haythami said in Majma` al-Zawa’id (2/263): “Its transmitters are those of authentic narrations.”
❖ Some of the Predecessors said: “Acting upon fear may be altered through hope, while acting out of love knows no waning.”  Jami` al-`Ulum wa al-Hikam, Ibn Rajab (2/341). Categories of Waning
A general laziness and lethargy in all acts of worship, disliking them and not wanting to engage in them. This is the state of the hypocrites. They are the most intense in their laziness, waning, and repulsion. Laziness and waning in some acts of worship, accompanied by a lack of desire to engage in it but with no dislike of it. There may be a desire for it, but weak. This is the state of many a miscreant Muslim who is immersed in his base desires. A general laziness and lethargy that has the body as its root cause, not the spirit. One has the desire for worship and loves to perform acts of obedience. He is saddened if he misses out on them. Nonetheless, he endures in his laziness and lethargy. Many nights may come and go in which he wished to sand in prayer, but he does not do this despite his awareness. This is the state of many Muslims afflicted by this condition. Among them are the righteous, while others are miscreants. A passing sense of waning and laziness. It does not persist nor stays for too long. It does not result in sin nor takes one out of obedience. No one is free from this type of waning, despite them being different in their being affected by it. Its cause is usually temporary; like tiredness, business, sickness, or the like.  See: al-Futur, Nasir al-`Umar (p. 24). Impacts of Waning
It is a sign of weak ambition. Lethargy towards worship. Risks personal and societal crises. Leads to neglecting some obligations. Its conclusion is evil if its possessor does not repent. Others being affected by its possessor, especially if he is in a position of authority. Missing out on worldly and religious benefits. Forms of Waning
Having a cruel heart. Laziness to perform acts of worship. Not sitting with the righteous. Wasting time and not using it efficiently for benefit. Lack of preparation in adhering to some matter, running away from any serious work. Chaos in one’s work. Deceiving oneself, that one is busy when in fact he is idle.  al-Futur, Nasir al-`Umar (p. 39). Having no protectiveness over nor anger at the desecration of Allah’s sanctity.  Ihya’ `Ulum al-Din al-Ghazali (3/169). Having no sense of responsibility.  al-Futur, Nasir al-`Umar (p. 37). Causes of Waning
Heedlessness of Allah and His remembrance. Zealousness in worship. Attaching oneself to people and clinging to them. Clinging to the worldly life and its adornments. Rarely remembering death and the Last Day. Poor nurture.  The previous source (p. 71). Means to Curing Waning
Supplicating for steadfastness upon religion. Remembrance of Allah, being consistent with the remembrance of the morn and the eve. Righteous company. Seeking forgiveness plentifully. Abundant recommended good deeds. Taking heed from the conclusion of those who wane. Contemplating over the Day of Resurrection.