Is it permissible to supplicate using the attribute "the Swift" (al-Saree') as mentioned in the Holy Quran, and to formulate a supplication from it such as: "O Swift, hasten the success of my request?"

"Sareea'" (swift/fast) is not one of Allah's Most Beautiful Names. However, it is mentioned in the Qur'an with a qualifier, such as in the verse "swift in account" (sareea' al-hisab). Therefore, it is not permissible to call upon Allah by this name alone without qualification. It is permissible to supplicate by saying "O Swift in Account" (Ya Sareea' al-Hisab) because Allah described Himself as such in the Qur'an. The swiftness of response does not mean immediate gratification in this world, as Allah may delay a response for a wisdom, or avert an evil with it, or save it for the Hereafter. "Account" (al-hisab) here includes monitoring deeds and recompensing for them, and delivering what has been promised to His servants.