اَللَّهُمَّ إِنِّي أَعُوْذُ بِكَ مِنَ الْبُخْلِ وَأَعُوْذُ بِكَ مِنَ الْجُبْنِ وَأَعُوْذُ بِكَ مِنْ أَنْ أُرَدَّ إِلَى أَرْذَلِ الْعُمُرِ وَأَعُوْذُ بِكَ مِنْ فِتْنَةِ الدُّنْيَا وَأَعُوْذُ بِكَ مِنْ عَذَابِ الْقَبْرِ

Allaahumma 'innee 'a'oodhu bika minal-bukhli, wa 'a'oodhu bika minal-jubni, wa 'a'oodhu bika min 'an 'uradda 'ilaa 'ardhalil-'umuri, wa 'a'oodhu bika min fitnatid-dunyaa wa 'a'oodhu bika min 'adhaabil-qabr

O Allah, I seek Your protection from miserliness, I seek Your protection from cowardice, and I seek Your protection from being returned to feeble old age. I seek Your protection from the trials of this world and I seek Your protection from the torment of the grave. Saad ibn Abi Waqqas (RA) used to teach these sentences to his sons in the same way that a teacher teaches handwriting to children. And he used to say that the Messenger of Allah (ﷺ) used to seek refuge (in Allah) in all these matters towards the end of the prayer - (The dua is mentioned above)

Reference: Bukhari: 6370