He said: "What harm is it to you if you do not do so, for there is no soul that will come into being until the Day of Resurrection except that it will indeed come into being."(1)

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(1) Its chain of transmission is authentic. Al-Qa'nabi: he is Abdullah ibn Maslamah, and Ibn Muhayriz: he is Abdullah al-Jumahi.
It is found in Malik's "Al-Muwatta" 2/594, and through his transmission al-Bukhari narrated it (2542).
Al-Bukhari also narrated it (4138), Muslim (1438), and al-Nasa'i in "Al-Kubra" (5026) and (5027) via the route of Rabi'ah ibn Abi Abd al-Rahman; al-Bukhari (7409) via the route of Musa ibn Uqbah; and al-Nasa'i (9041) via the route of al-Dahhak ibn Uthman — all three of them from Muhammad ibn Yahya ibn Habban, with it.
Al-Bukhari also narrated it (2229), (5210), and (6603), Muslim (1438), and al-Nasa'i in "Al-Kubra" (5024), (5025), (5028), (9039), and (9040) via the route of Ibn Shihab al-Zuhri, from Abdullah ibn Muhayriz, with it.
Muslim narrated it (1438), and al-Nasa'i in "Al-Kubra" (5029) via the route of Ma'bad ibn Sirin; Muslim (1438), and al-Nasa'i in "Al-Kubra" (5030), (5462), and (9046) via the route of Abd al-Rahman ibn Bishr ibn Mas'ud; Muslim (1438) via the route of Abi al-Waddak; Ibn Majah (1926), and al-Nasa'i in "Al-Kubra" (9037) via the route of Ubaydullah ibn Abdullah; and al-Nasa'i in "Al-Kubra" (9038) via the route of Ata' ibn Yazid — all five of them from Abu Sa'id al-Khudri.
See also "Sunan al-Nasa'i al-Kubra" (5030) and (9046).
It is in "Musnad Ahmad" (11647) and "Sahih Ibn Hibban" (4193).
Al-Nawawi said in "Sharh Muslim": This hadith contains evidence for the view of the majority of scholars that enslavement applies to the Arabs just as it applies to non-Arabs, and that if they are polytheists and are taken captive, it is permissible to enslave them. This is the view of Malik and al-Shafi'i in his correct new opinion, and the majority of scholars. Abu Hanifah and al-Shafi'i in his old opinion said: enslavement does not apply to them.
We say: In "Al-Hidayah," one of the Hanafi books, it is stated that enslaving Arab men is not permissible in their view, but enslaving their women and children is permissible.
His saying: "We preferred the ransom" — and in Muslim's version: "and we desired the ransom" — the meaning of "ransom" here is the value, i.e., we feared that if we had intercourse with them, they would become pregnant, and then it would not be possible to sell them, and we desired that the value should be obtained for us. =