Muhammad bin Harun al-Miski heard Imam Muhammad bin Isma'il al-Bukhari (may Allah have mercy on him) when he was asked about the hadith of Isra'il, from Abu Ishaq, from Abu Burdah, from his father (may Allah be pleased with him), from the Prophet (peace and blessings be upon him): "There is no marriage without a guardian." Imam al-Bukhari (may Allah have mercy on him) said: An addition from a trustworthy narrator is accepted, and Isra'il bin Yunus is thiqah (trustworthy); even if Shu'bah and al-Thawri narrated it as mursal (without the Companion), that does not harm the hadith.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب النكاح / 13622