Hadithcore
Sahih al-Bukhari, 3772
sahih

Narrated Abu Wail:

When `Ali sent `Ammar and Al-Hasan to (the people of) Kufa to urge them to fight, `Ammar addressed them saying, "I know that she (i.e. `Aisha) is the wife of the Prophet (ﷺ) in this world and in the Hereafter (world to come), but Allah has put you to test, whether you will follow Him (i.e. Allah) or her."

حَدَّثَنَا مُحَمَّدُ بْنُ بَشَّارٍ، حَدَّثَنَا غُنْدَرٌ، حَدَّثَنَا شُعْبَةُ، عَنِ الْحَكَمِ، سَمِعْتُ أَبَا وَائِلٍ، قَالَ لَمَّا بَعَثَ عَلِيٌّ عَمَّارًا وَالْحَسَنَ إِلَى الْكُوفَةِ لِيَسْتَنْفِرَهُمْ خَطَبَ عَمَّارٌ فَقَالَ إِنِّي لأَعْلَمُ أَنَّهَا زَوْجَتُهُ فِي الدُّنْيَا وَالآخِرَةِ، وَلَكِنَّ اللَّهَ ابْتَلاَكُمْ لِتَتَّبِعُوهُ أَوْ إِيَّاهَا‏.‏

References2 variants
In-Book Reference
Book 62, Hadith 117
USC-MSA web (English) reference
Vol. 5, Book 57, Hadith 116 (deprecated numbering scheme)