The Messenger of Allah (ﷺ) used to say in prayer:

اَللَّهُمَّ إِنِّي أَسْأَلُكَ الثَّبَاتَ فِي الْأَمْرِ وَالْعَزِيْمَةَ عَلَى الرُّشْدِ وَأَسْأَلُكَ شُكْرَ نِعْمَتِكَ وَحُسْنَ عِبَادَتِكَ وَأَسْأَلُكَ قَلْبًا سَلِيْمًا وَلِسَانًا صَادِقًا وَأَسْأَلُكَ مِنْ خَيْرِ مَا تَعْلَمُ وَأَعُوذُ بِكَ مِنْ شَرِّ مَا تَعْلَمُ وَأَسْتَغْفِرُكَ لِمَا تَعْلَمُ

Allaahumma inni as'aluka ath-thabbaata fil-amri wal-'azimata 'alar-rushdi wa as'aluka shukra ni'matika wa ‘husna 'ibaadatika wa as'aluka qalban saliman wa lisaanan sadiqan wa as'aluka min khairi maa ta'lamu wa A‛oodhu bika min sharri maa ta'lamu wa astaghfiruka limaa ta'lamu

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.

Reference: Sahih Li Ghairihi. Takhrij Mishkat: 915