From Sahih Muslim (Hadith 405):
This hadith has been reported from 'A'isha by another chain of transmitters and the words are:He (the Holy Prophet) came to Khadija an his heart was trembling. The rest of the hadith has been narrated like one transmitted by Yunus and Ma'mar, but the first part is not mentioned, i. e. the first thing with which was started the revelation to the Prophet was the true vision. And these words like those transmitted by Yunus are mentioned thus: By Allah, Allah would never humiliate you. And there is also a mention of the words of Khadija: O son of my uncle! Listen to the son of your brother
Reference: Muslim 405