ANSWER:
Allaahumma inni astakheeruka bi ‘ilmika wa astaqdiruka bi qudratika wa as’aluka min fadlika, fa innaka taqdiru wa laa aqdir, wa ta’lamu wa laa a’lam, wa anta ‘allaam al-ghuyoob. Allaahumma fa in kunta ta’lamu haadha’l-amra (then the matter should be mentioned by name) khayran li fi ‘aajil amri wa aajilihi (or: fi deeni wa ma’aashi wa ‘aaqibati amri) faqdurhu li wa yassirhu li thumma baarik li fihi. Allaahumma wa in kunta ta’lamu annahu sharrun li fi deeni wa ma’aashi wa ‘aaqibati amri (or: fi ‘aajili amri wa aajilihi) fasrifni ‘anhu [wasrafhu ‘anni] waqdur li al-khayr haythu kaana thumma radini bihi (O Allaah, I seek Your guidance [in making a choice] by virtue of Your knowledge, and I seek ability by virtue of Your power, and I ask You of Your great bounty. You have power, I have none. And You know, I know not. You are the Knower of hidden things. O Allaah, if in Your knowledge, this matter (then it should be mentioned by name) is good for me both in this world and in the Hereafter (or: in my religion, my livelihood and my affairs), then ordain it for me, make it easy for me, and bless it for me. And if in Your knowledge it is bad for me and for my religion, my livelihood and my affairs (or: for me both in this world and the next), then turn me away from it, [and turn it away from me], and ordain for me the good wherever it may be and make me pleased with it).” Narrated by al-Bukhaari in several places in his Saheeh (1166).
You will find this and many other djikr and duas in a booklet called ‘Hisnul Muslim’, in English its called ‘Fortress of the Muslim’.