It was narrated from Shadad bin Aws that

The Messenger of Allah (ﷺ) used to say in his prayer: "Allahumma inni as'aluka at-thabbuta fi al-amr wal-'azimata 'alar-rushdi wa as'aluka shukr ni'matik wa husna 'ibadatik wa as'aluka qalban saliman wa lisanan sadiqan wa as'aluka min khairi ma at'lamu wa author bika min sharri ma at'lamu wastaghfiruka lima ta'lam (O Allah, I ask You for steadfastness in all my affairs and determination in following the right path, I ask You to make me thankful for Your blessings and to make me worship You properly. I ask You for a sound heart and a truthful tongue. I ask You for the best of what You know and I seek refuge in You from the worst of what You know and I seek Your forgiveness for what You know.)"