Hisham bin Urwah narrated from his father that he said: "Sometimes I hear a hadith and I like it, but I do not narrate it because someone who hears it might act upon it, while I have heard it from a person whom I do not consider reliable, even though he has narrated it from someone whom I do consider reliable. And sometimes I hear it from a trustworthy person while he is narrating it from someone who is not trustworthy." Sa‘d bin Ibrahim said: "No one should narrate hadiths from the Prophet ﷺ except trustworthy narrators."
Hadith Referenceمسند الإمام الشافعي / كتاب فضائل قريش وغيرهم وأبواب متفرقة / 1812
Yahya bin Saeed narrated that Abdullah bin Umar (may Allah be pleased with them) was asked about an issue, but he did not give any answer. Then it was said to him: "We find it very (strange) that you are the son of two rightly guided Imams (i.e., Umar and Ibn Umar, may Allah be pleased with them), and you are asked about an issue while you do not have knowledge about it?" So he replied: "An even stranger thing in the sight of Allah, and for the one who recognizes Allah, and for the one who has understanding from Allah, is that I should say something about which I have no knowledge, or that I should narrate something from an unreliable (narrator)."
Hadith Referenceمسند الإمام الشافعي / كتاب فضائل قريش وغيرهم وأبواب متفرقة / 1813
Muhammad bin Idris (Shafi'i), may Allah have mercy on him, said: "I have narrated mursal ahadith from the Prophet ﷺ regarding punishments and the determination of their times, but we have abandoned them only because of their being disconnected."
Hadith Referenceمسند الإمام الشافعي / كتاب فضائل قريش وغيرهم وأبواب متفرقة / 1814