ENOfficial
‘Abdallah b. ‘Amr reported God’s messenger as saying, "When a man comes to visit an invalid he should say, ‘O God, cure Thy servant who may then wreak havoc on an enemy for Thy sake, or walk at a funeral for Thy sake’.” Abu Dawud transmitted it.
Source: sunnah.com
Other translations
Arabic
وَعَنْ عَبْدِ اللَّهِ بْنِ عَمْرٍو قَالَ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: «إِذَا جَاءَ الرجل يعود مَرِيضا فَلْيقل ك اللَّهُمَّ اشْفِ عَبْدَكَ يَنْكَأُ لَكَ عَدُوًّا أَوْ يَمْشِي لَكَ إِلَى جِنَازَةٍ» رَوَاهُ أَبُو دَاوُدَ
sunnah.com