Ibn Umar (may Allah be pleased with them both) said that the Prophet (peace and blessings be upon him) killed a Muslim in return for a dhimmi and said: "I am the one most faithful in fulfilling my covenant of protection."
There are two defects in this narration: (1) Making it connected through Ibn Umar (may Allah be pleased with them both) is a mistake; rather, it is a mursal narration of (Ibn) al-Baylamani from the Prophet (peace and blessings be upon him). (2) Ibrahim narrates it from Ibn al-Munkadir, and the fault in it is attributed to Ammar bin Matar al-Rahawi, who used to switch chains of narration and steal hadith; he is a narrator who has fallen below the level of being used as evidence.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الجنايات / 15917
Abd al-Rahman bin al-Baylamani (may Allah have mercy on him) narrates, attributing it to the Prophet (marfu'), that a Muslim killed a dhimmi, and the Prophet (peace and blessings be upon him) said: "I am the one most faithful in fulfilling a covenant of protection." Then he (peace and blessings be upon him) had that Muslim killed. This narration is munqati' (has a broken chain), and its narrator is not trustworthy.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الجنايات / 15918
Abd al-Rahman bin al-Baylamani said: A man from among the dhimmis came to the Prophet (peace and blessings be upon him) and said: We had such-and-such an agreement with you. One of your men has killed one of our men. He (peace and blessings be upon him) said: "I have the greatest right to fulfil my covenant of protection." So he (peace and blessings be upon him) had that Muslim killed.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الجنايات / 15919
Ibn al-Baylamani (may Allah have mercy on him) narrates, attributing it to the Prophet (marfu'), that a Muslim killed a Jew (and in the narration of al-Ramadi: a dhimmi), so that Muslim was killed in retaliation, and he (peace and blessings be upon him) said: "I am the most entitled to fulfil my covenant of protection."
It is said that Rabi'ah only took it from Ibrahim bin Muhammad bin Abi Yahya, and the hadith revolves around him.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الجنايات / 15920
Ibn al-Baylamani (may Allah have mercy on him) narrates that the Prophet (peace and blessings be upon him) killed a Muslim in return for a dhimmi and said: "I have the greatest right to fulfil my covenant of protection."
Abu Ubayd (may Allah have mercy on him) said: Then it reached me that Ibn Abi Yahya said: It was I who narrated this hadith to Rabi'ah; so the hadith revolves only around Ibn Abi Yahya. This hadith is not musnad, and a narration like it should not be made an authority on the basis of which the blood of Muslims is shed. Abu Ubayd (may Allah have mercy on him) said: Abd al-Rahman bin Mahdi (may Allah have mercy on him) told me, through Abd al-Wahid bin Ziyad (may Allah have mercy on him), that he said: I said to Zufar (may Allah have mercy on him): You say that we avert the hadd punishments because of doubts, yet you yourselves bring the greatest doubt. He said: What is that? I said: That a Muslim is to be killed in return for a disbeliever. Imam Zufar (may Allah have mercy on him) said: Be my witness that I retract this. Abu Ubayd (may Allah have mercy on him) said: This is also the position of the people of the Hijaz, that a Muslim is not to be killed (for him). As for his saying, "nor one who has a covenant during his covenant": when a person from Dar al-Harb comes to the Muslims, he too is not to be killed until he returns, because Allah Almighty says: "And if any one of the polytheists seeks your protection, then grant him protection so that he may hear the word of Allah, then convey him to his place of safety." [Surah al-Tawbah: 6]
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الجنايات / 15921
Abd al-Wahid bin Ziyad (may Allah have mercy on him) said: I said to Imam Zufar (may Allah have mercy on him): You have become a topic of talk and a laughingstock among the people. He asked: How so? I said: You say that the hadd is to be averted when there is doubt, yet you yourselves establish a very grave hadd despite doubt. He asked: How is that? I said: He (peace and blessings be upon him) said: "A believer will not be killed in return for a disbeliever," and you say that he will be killed. Imam Zufar (may Allah have mercy on him) said: I make you my witness that I have retracted it.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الجنايات / 15922
Ali bin al-Madini (may Allah have mercy on him) said: The narration of Ibn al-Baylamani, attributed to the Prophet (marfu'), that "a Muslim was killed in return for a dhimmi," revolves around Ibn Abi Yahya; it has no route that can serve as proof, and (Rabi'ah) only took it from him.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الجنايات / 15923
Salih bin Muhammad al-Hafiz (may Allah have mercy on him) said: The hadith of Abd al-Rahman bin al-Baylamani is munkar (rejected). That which Rabi'ah (may Allah have mercy on him) narrated from him, that "the Prophet (peace and blessings be upon him) killed a Muslim in return for a dhimmi," is also mursal and munkar.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الجنايات / 15924
Abu al-Hasan Ali bin Umar al-Daraqutni al-Hafiz (may Allah have mercy on him) said: Ibn al-Baylamani is da'if (weak); no proof can be taken from him even when he narrates a hadith with a connected chain, so how about what he narrates mursal? 'Wallahu a'lam' (And Allah knows best).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الجنايات / 15925