Qatada asked Anas which Supplication Allah's Messenger (ﷺ) frequently made. He said: The supplication that he (the Prophet (ﷺ) made very frequently is this:" O Allah, grant us the good in this world and the good in the Hereafter and save us from the torment of Hell-Fire." He (Qatada) said that whenever Anas had to supplicate he made this very supplication, and whenever he (intended) to make another supplication he (inserted) this very supplication in that.
Source: sunnah.com
Other translations
Arabic
حَدَّثَنِي زُهَيْرُ بْنُ حَرْبٍ، حَدَّثَنَا إِسْمَاعِيلُ، - يَعْنِي ابْنَ عُلَيَّةَ - عَنْ عَبْدِ الْعَزِيزِ، - وَهُوَ ابْنُ صُهَيْبٍ - قَالَ سَأَلَ قَتَادَةُ أَنَسًا أَىُّ دَعْوَةٍ كَانَ يَدْعُو بِهَا النَّبِيُّ صلى الله عليه وسلم أَكْثَرَ قَالَ كَانَ أَكْثَرُ دَعْوَةٍ يَدْعُو بِهَا يَقُولُ " اللَّهُمَّ آتِنَا فِي الدُّنْيَا حَسَنَةً وَفِي الآخِرَةِ حَسَنَةً وَقِنَا عَذَابَ النَّارِ " . قَالَ وَكَانَ أَنَسٌ إِذَا أَرَادَ أَنْ يَدْعُوَ بِدَعْوَةٍ دَعَا بِهَا فَإِذَا أَرَادَ أَنْ يَدْعُوَ بِدُعَاءٍ دَعَا بِهَا فِيهِ .
sunnah.com