How can one prolong standing after bowing (Qiyam ba'da al-ruku') in the night prayer (Salat al-Layl) to match the standing of the Prophet (peace be upon him), given the brevity of the authentically transmitted invocations (adhkar)?

It is from the Sunnah for the worshipper to recite the prescribed supplications (adhkar) after rising from genuflection (ruku'). Among the most complete of these is what is narrated in Sahih Muslim: "Our Lord, to You be praise, filling the heavens and the earth, and filling whatever else You wish thereafter. O You who are worthy of praise and glory, the truest thing a servant has said, and all of us are servants to You. O Allah, there is none to withhold what You have given, and none to give what You have withheld, and the might of the mighty will not benefit them against You." If one wishes to prolong this, he may repeat it or recite other formulas established in the Sunnah, or supplicate with whatever he wishes.