A‘isha told that God’s messenger was questioned about Waraqa and Khadija said to him, “He believed on you, but died before you appeared as a prophet.” God’s messenger then said: “I was shown him in a dream wearing white clothes, and if he had been one of the inhabitants of hell he would have been wearing different clothing.” Ahmad and Tirmidhi transmitted it.
Source: sunnah.com
Other translations
Arabic
وَعَنْ عَائِشَةَ رَضِيَ اللَّهُ عَنْهَا قَالَتْ سُئِلَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ عَن وَرَقَةَ. فَقَالَتْ لَهُ خَدِيجَةُ: إِنَّهُ كَانَ قَدْ صَدَّقَكَ وَلَكِنْ مَاتَ قَبْلَ أَنْ تَظْهَرَ. فَقَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: «أُرِيتُهُ فِي الْمَنَامِ وَعَلَيْهِ ثِيَابٌ بِيضٌ وَلَوْ كَانَ مِنْ أَهْلِ النَّارِ لَكَانَ عَلَيْهِ لِبَاسٌ غَيْرُ ذَلِك» . رَوَاهُ أَحْمد وَالتِّرْمِذِيّ
sunnah.com