ENOfficial
Hisham ibn 'Urwa reported that his father said, "I was sitting with Mu'awiya and he muttered to himself and then came to his senses. He said, 'No one has forbearance without it being put to the test.' He repeated that three times."
Source: sunnah.com
Other translations
Arabic
حَدَّثَنَا فَرْوَةُ بْنُ أَبِي الْمَغْرَاءِ، قَالَ: حَدَّثَنَا عَلِيُّ بْنُ مُسْهِرٍ، عَنْ هِشَامِ بْنِ عُرْوَةَ، عَنْ أَبِيهِ قَالَ: كُنْتُ جَالِسًا عِنْدَ مُعَاوِيَةَ، فَحَدَّثَ نَفْسَهُ، ثُمَّ انْتَبَهَ فَقَالَ: لاَ حِلْمَ إِلاَّ تَجْرِبَةٌ، يُعِيدُهَا ثَلاثًا.
sunnah.com