Grading: (1) There is no harm in its narrators, but Muhammad bin Ishaq is a "mudallis" and he did not explicitly state that he heard it from Muhammad bin al-Munkadir.
Technical note / Defect ('illah): Imam al-Bukhari, in "al-Tarikh" 1/ 244, expressed doubt about his having heard from him, and said: "And some of them said: Muhammad bin Ishaq did not hear from Ibn al-Munkadir." Then he said: "And this is a hadith in which he was not corroborated."
Important point: We say: he has also been contradicted by those who are more trustworthy than him, for they narrated it as "mursal".

Reference / Source: It was also recorded by al-Bazzar (5965), al-Nasa'i (5284), and al-Bayhaqi in "al-Sunan al-Kubra" 8/ 314 and in "Ma'rifat al-Sunan wa al-Athar" (17394), via Muhammad bin Musa al-Harashi, with this same isnad.
Details of the narration: And they added the words: "So the Muslims understood that the hadd punishment had taken place (had been applied), and that the ruling of execution had been lifted."

Reference / Source: It was also recorded similarly by al-Bukhari in "al-Tarikh al-Kabir" 1/ 244 and al-Uqayli in "al-Du'afa'" (1658) via Muhammad bin al-Mu'alla al-Iyami, and by al-Nasa'i (5283) and al-Tahawi in "Sharh al-Ma'ani" 3/ 161 via Sharik al-Nakha'i, both of them from Ibn Ishaq, in the same way.

Technical note / Defect ('illah): Al-Hasan bin Salih bin Hayy contradicted them all (in al-Khatib's "al-Asma' al-Mubhamah" p. 307): he narrated it from Ibn Ishaq, from Abd al-Malik bin Abi Bakr, from Ibn al-Munkadir. Thus he added "Abd al-Malik bin Abi Bakr" between Ibn Ishaq and Ibn al-Munkadir. But this is an isnad not worth rejoicing over (i.e. it is weak), because in the route leading to Ibn Ishaq there is "Ahmad bin Muhammad bin al-Sari al-Tamimi", who is accused of lying; and likewise Ibn Ishaq did not explicitly state in it that he heard from Abd al-Malik.

Technical note / Defect ('illah): Ibn Ishaq was contradicted by "Ma'mar" (as passed after 8315), by "Amr bin al-Harith al-Misri" (in al-Tahawi 3/ 161), and by "Ibn Jurayj" (as al-Tirmidhi mentioned in his "Jami'" after 1444). All of them narrated it from Ibn al-Munkadir as "mursal", without mention of Jabir (may Allah be pleased with him) in it. And the isnad of the routes of Ma'mar and Amr bin al-Harith is "sahih" up to Ibn al-Munkadir.

Reference / Source: It was also recorded similarly by Abd al-Razzaq (13552) and (17082) and Ibn Sa'd in "al-Tabaqat" 3/ 458 via Ma'mar, from Zayd bin Aslam as "mursal"; he said: The son of al-Nu'ayman was brought to the Prophet (peace and blessings be upon him) repeatedly (more than four times), and each time he had him flogged. A man who was with the Prophet (peace and blessings be upon him) said: "O Allah, curse him! How often he drinks, and how often he is flogged!" At that the Prophet (peace and blessings be upon him) said: "Do not curse him, for he loves Allah and His Messenger."