Overall Meaning: Meaning of desertion:
Khidhlan linguistically: Khadhalahu khidhlanan (he deserted him) is used when one does not help another nor back them up. Takhdhil is inciting a person to desert his companion, pulling him away from his support. The khadhil is the defeated one. [937] Tahdhib al-Lughah, al-Azhari (7/140); al-Sihah, al-Jawhari (4/1683); Lisan al-`Arab, Ibn Manzur (11/202).
Khidhlan technically: It is abandoning the one whose support would be expected, not aiding nor rescuing them. [938] al-Mufradat, al-Raghib (p. 277); Fath al-Qadir, al-Shawkani (1/451) and (4/85).

Dispraise of desertion and warning against it in the Qur’an and Sunnah:
❖ Allah, exalted, says, “Set up no other god beside Allah, or you will end up disgraced and forsaken.” (al-Isra’: 22)
❖ He, exalted, also says, “On that Day the evildoer will bite his own hand and say: ‘If only I had taken the same path as the Messenger. Woe is me! Would that I had not taken such a one for a friend! He led me away from the Reminder after it reached me. Satan has always betrayed mankind.’” (al-Furqan: 27 - 29)
❖ Abu Hurayrah, Allah be pleased with him, said, “Allah’s Messenger ﷺ said, ‘The Muslim is the brother of the Muslim; he does not oppress, desert, or belittle him.’” [939] Reproted by Muslim (2564).
❖ Mu`awiyah ibn Qurrah, Allah be pleased with him, said, “I heard the Messenger of Allah ﷺ say, ‘There will always be a group from my Ummah upright in fulfilling Allah’s commands. Those who desert them and go against them will not harm, until Allah’s promise reaches them upon this.’” [940] Reported by al-Bukhari (3641) and Muslim (1037).

Quotes of the Predecessors and scholars on desertion:
❖ It was said to Muhammad ibn Ka`b al-Qurazi, “What is the sign of desertion?” He replied, “That one finds the good he had ugly, and the ugly he has good.” [941] al-Bayan wa al-Tabyin, al-Jahiz (2/199).
❖ `Ali ibn `Ubaydah said, “The intellect and one’s whims are opposites. The helper of the intellect is harmonisation, whilst the partner of whims is desertion. The self is in between them - whichever one is victorious, it is on its side.” [942] Tashil al-Nazar, al-Mawardi (p. 14).
❖ Ibn al-Qayyim said, “Some of the saints said, ‘the saintly are in consensus that success is that Allah does not entrust you to yourself. They are also in consensus that desertion is that he leaves no barrier between you and your self.’” [943] Miftah Dar al-Sa`adah, Ibn al-Qayyim (1/132).

Impacts and harms of desertion:
1- The spread of selfishness and narcissism. 
2- Prioritising comfort, placing personal benefit over public benefit. 
3- Lack of chivalry, such that there is no sense of rescuing the needy and delivering the troubled.
4- The severance of brotherly ties among the Muslims. 
5- Desertion is a cause of defeat. It is a shame which befalls its possessor.

Forms of Desertion:
1- Deserting the oppressed when able to back him up. 
2- Letting the oppressor down by not advising him to desist from his tyranny. 
3- Deserting the Muslims when battling for the sake of Allah, not seeking to give them victory. This is a trait of the hypocrites.

Reasons for falling into desertion:
1- Distancing oneself from brotherly faith. 
2- Seeking aid in other than Allah. 
3- Obedience to the disbelievers and the hypocrites. 
4- Leaving off brotherhood that is for Allah's sake. 
5- Leaning towards the tyrants. Loving the worldly life, hating death, and immersion in frolic and comfort. 
6- Self-amazement. 
7- Cowardice and poor judgement. 
8- Discontentment with divine destiny and decree.

Means to desisting from the causes of desertion:
1- Beneficence to the people in all its forms. 
2- Seeking Allah’s aid. 
3- Not having self-amazement, and instead showing humility and neediness before Allah. 
4- Contentment with Allah’s destiny and decree, not fearing the repercussions of giving others backup. 
5- Maintaining ties of kinship and close relations.

Desertion in adages, proverbs, and poetry:
❖ “Desertion comes from the many, and togetherness comes from the few.” Many and few here refers to men in an army. [944] Majma` al-Amthal, al-Maydani (1/61)
❖ “The one who gains so-and-so, gains the losing arrow.” This is a parable for the one who is deserted at the time of need. [945] Al-Tadhkirah al-Hamduniyyah, Ibn Hamdun (7/144)
❖ `Abd al-`Anbari said,
“When Allah wishes humiliation for some nation,
He allows for differing whims and desertion therein.” [946] Sayd al-Afkar, al-Qadi Husayn al-Mahdi (2/136).