Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) narrates: I said: O Messenger of Allah, what is your view if we face a matter about which no Qur'an has been revealed and for which there is no Sunnah from you? The Prophet (peace and blessings be upon him) said: Present it for mutual consultation among the worshippers from among the believers, and do not give a judgement on it based on the opinion of any one particular person. The narrator then related the full hadith; this complete hadith will come later in the chapter on analogy (qiyas).
Al-Tabarani recorded it in al-Mu'jam al-Kabir; its chain contains a narrator, Abdullah bin Kaysan, about whom Imam Bukhari (may Allah have mercy on him) said: He is munkar al-hadith (his narrations are rejected).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب العلم / 833