The story of the name
The only companion named in the Qur'an
Of all the men and women who surrounded the Prophet ﷺ — the giants of Badr, the veterans of every sacrifice — exactly one companion's name is written in the Qur'an: so when Zayd had concluded from her what he needed (Surah al-Ahzab, 33:37). The scholars stand in awe of the choice. A ruling that dismantled a deep-rooted custom needed a name attached, and Allah chose the name of a man whose honor could carry it — his place in the mushaf fixed until the end of time.
Chosen to break an old custom
The Prophet ﷺ had arranged Zayd(RA)'s marriage to Zaynab bint Jahsh (RA); the marriage ended in divorce. Afterward, Allah commanded the Prophet ﷺ to marry her — and the Qur'an states the reason directly: so that there would be no difficulty for the believers concerning the wives of their adopted sons, once they have ended their relationship with them (Surah al-Ahzab, 33:37). The Qur'an, thus, abolished the pre-Islamic rule treating adopted sons exactly like biological sons in marriage law.
The one who chose
Zayd ibn Harithah (RA) had been torn from his family as a boy and sold into slavery, until fortune placed him in the household of Muhammad ﷺ. When his father and uncle finally traced him and came to ransom him, he was given a free choice — and chose to stay with the Prophet ﷺ over his own kin. He had seen something worth more than home. The Prophet ﷺ freed him on the spot, and Zayd went on to be counted among the very earliest believers, embracing Islam at the outset of the Prophet's ﷺ mission alongside Khadijah(RA), Ali(RA), Abu Bakr(RA), and Bilal(RA).
From Zayd ibn Muhammad to Zayd ibn Harithah
Before Islam, an adopted son was treated in law exactly as a biological one — and the Prophet ﷺ had adopted Zayd, who became known across Makkah as Zayd ibn Muhammad. The Qur'an later reformed this custom directly: "Allah has not made your adopted sons your true sons... call them by the names of their fathers; that is more just in the sight of Allah" (Surah al-Ahzab, 33:4–5). From that point he was known once more as Zayd ibn Harithah. Ibn Umar said plainly: we never called him anything but Zayd ibn Muhammad, until the Qur'an revealed call them by their fathers (Bukhari 4782). The reform simply restored his lineage while the love remained exactly what it was.
Martyrdom at Mu'tah
The Prophet ﷺ trusted Zayd with command again and again, and at Mu'tah gave him the highest trust of all: first in the line of command, with Ja'far ibn Abi Talib(RA) to follow him and Abdullah ibn Rawahah(RA) after that. Zayd (RA) fell first, standard in hand, against the armies of Rome. The freed slave who once chose the Prophet ﷺ over his own family gave him, at the end, everything he had left to give.
Al-Hibb ibn al-Hibb
The love was no secret and it did not end with him. The Prophet ﷺ said of Zayd (RA)'s son Usamah (RA): the most beloved of people to me — "and his father before him" (Bukhari 3730) — and the ummah remembers them together by a single title, al-hibb ibn al-hibb, the beloved, son of the beloved. His name means growth and increase, and his life defines it: a captive boy who increased, and increased, until revelation itself wrote him in.
To carry this name
To carry this name is to grow wherever you are planted — a captive who became the beloved, a freedman whose name outlasts empires because it is written in revelation. Increase is the meaning; increase in love earned is the biography.