Sayyiduna Ubadah bin al-Samit (may Allah be pleased with him) reports this saying of the Prophet (peace and blessings be upon him): "The dream of a believer is speech by which his Lord speaks to the servant in sleep."
Al-Tabarani recorded it, and its chain contains a narrator whom I do not know. Hadiths of this kind will come later in the chapter on one who sees a dream that he likes.
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب التعبير / 11728