What is the recommended remembrance after completing the Witr prayer?

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It is recommended to recite "Subhana al-Malik al-Quddus" (Glory be to the Sovereign, the Most Holy) three times after finishing the Witr prayer. This recitation must be elongated in the third repetition. This is supported by the narration of Ubayy ibn Ka'b, who stated that the Messenger of Allah, peace and blessings be upon him, used to say this after concluding Witr. Another narration from Abd al-Rahman ibn Abza confirms that the Prophet, peace and blessings be upon him, recited specific Surahs in Witr and, upon intending to depart, would say "Subhana al-Malik al-Quddus" three times, raising his voice in the third.