Grading: On account of Abd al-Malik bin al-Rabi' (bin Sabrah), this chain is "hasan" in corroborating chains and supporting reports, though there is shudhudh (irregularity) in its wording.
Technical note / Defect ('illah): Ya'qub bin Ibrahim is alone in the wording "When your children reach seven years of age, separate their beds." Ibn Abi al-Dunya in "al-Iyal" (294) and al-Daraqutni in "al-Sunan" (886) also narrated it this way by his route. However, everyone else who narrated this hadith from Abd al-Malik bin al-Rabi' differed from him, narrating it with the wording: "When the boy reaches seven years of age he is to be ordered to pray, and when he reaches ten he is to be beaten for (neglecting) it," and this is the mahfuz (preserved) wording. Ahmad 24/(15339), Abu Dawud (494), al-Tirmidhi (407) and others recorded it by various routes from Abd al-Malik bin al-Rabi'. It will come with the author (al-Hakim) under number (961) by way of Harmalah bin Abd al-Aziz from Abd al-Malik. What follows it serves as a supporting report for it.