The Prophet ﷺ said, "Any slave who marries without his master's permission is a fornicator."
قال النبي ﷺ: أيما عبد تزوج بغير إذن سيده، فهو عاهر.
Abu Dawud (2078), Tirmidhi (1112, 1111 [as noted, though this appears to be a numbering issue in the source]), and Ibn Majah (1959) all narrated it, and Hakim (2/194) graded it sahih, all of them from the hadith of Abdullah bin Muhammad bin Aqeel, from Jabir, as mentioned, except that Ibn Majah said in it "from Ibn Umar," which is not preserved correctly. Tirmidhi said, "In the first instance, hasan, and in the second instance, hasan sahih." Hakim said, "sahih in isnad."Its isnad is hasan due to the discussion regarding Abdullah bin Muhammad bin Aqeel, though his hadith is hasan, as I have clarified in several places in the book. As for what has been narrated from Ibn Umar as a similar raised report, it is daif.Abu Dawud (2079) narrated it from Uqba bin Mukram, who said, Abu Qutayba narrated to us, from Abdullah bin Umar, from Nafi, from Ibn Umar, as mentioned. Abu Dawud said, "This hadith is daif, and it is a stopped report, and it is the statement of Ibn Umar." I say, this is because it contains Abdul-Rahman bin Umar Umari, who is daif by the agreement of the people of knowledge.Ibn Majah also narrated it (1960) from Muhammad bin Yahya and Salih bin Muhammad bin Yahya bin Saeed, who both said, Abu Ghassan Malik bin Ismail narrated to us, who said, Mindal narrated to us, from Ibn Jurayj, from Musa bin Uqba, from Nafi, from Ibn Umar, who said, the Messenger of Allah ﷺ said, "Any slave who marries without the permission of his masters is a fornicator." This contains Mindal, who is Ibn Ali Anazi, "daif" as stated in Taqrib, and his teacher Ibn Jurayj is a mudallis, and he has narrated with an ambiguous transmission form (an).As for the stopped report attributed to Ibn Umar, this is what Bayhaqi narrated (7/127) from Abdullah bin Numayr, from Abdullah bin Umar, from Nafi, from Ibn Umar, that he used to hold the view that the marriage of a slave without his master's permission is fornication, for which the one who married him off is to be punished. This also contains Abdullah bin Umar Umari, who is daif, as mentioned previously.The conclusion is that it is not sound from Ibn Umar, whether as a raised report or as a stopped one.