The Messenger of Allah (ﷺ) used to pray like this:

اَللَّهُمَّ احْفَظْنِيْ بِالْإِسْلَامِ قَائِمًا، وَاحْفَظْنِيْ بِالْإِسْلَامِ قَاعِدًا، وَاحْفَظْنِيْ بِالْإِسْلَامِ رَاقِدًا، وَلَا تُشْمِتْ بِي عَدُوًّا وَلَا حَاسِدًا اَللَّهُمَّ إِنِّي أَسْأَلُكَ مِنْ كُلِّ خَيْرٍ خَزَائِنُهُ بِيَدِكَ، وَأَعُوْذُ بِكَ مِنْ كُلِّ شَرٍّ خَزَائِنُهُ بِيَدِكَ

Allaahumma’h-fazni bil’islaami qaa’iman, wa’h-fazni bil’islaami qaa‛idan, wa’h-fazni bil’islaami raa-qidan, wa laa tushmit bee ‛adu-wan wa laa ’haasidan, Allaahumma innee as’aluka min kulli khayrin khazaa’inuhu bi-yadik, wa a‛oodhu bika min kulli sharrin khazaa’inuhu biyadik

O Allah! Protect me with Islam when standing, and protect me with Islam when sitting down, and protect me with Islam when reclining, and do not make an enemy or envier gloat over me. O Allah, I ask you for every good whose treasuries are in Your Hand, and I seek refuge with you from every evil whose treasuries are in Your Hand.

Reference: Hasan (Albani). Silsilatul Sahiha: 1540