Abu Dawud al-Sijistani says: This hadith is not strong; a prohibition of this has been narrated from many of the Companions.
The Shaykh says: The hadith masters are wary of what Ibn Ishaq alone narrates. And if this is authentic, then perhaps the prohibition had not reached Sayyiduna Ja'far (may Allah be pleased with him).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب السير / 18138