From Sahih Bukhari (Hadith 3393):
Narrated Malik bin Sasaa:Allah's Messenger (ﷺ) talked to his companions about his Night Journey to the Heavens. When he reached the fifth Heaven, he met Aaron. (Gabriel said to the Prophet), "This is Aaron." The Prophet (ﷺ) said, "Gabriel greeted and so did I, and he returned the greeting saying, 'Welcome, O Pious Brother and Pious Prophet
Reference: Bukhari 3393