Ibn Ḥibbān records it with the wording: “then whatever you wish.”⦗1⦘

Vocabulary of the ḥadith:
– asbagha: From the verb sabaga yasbughu subūghan, meaning “to be complete and perfect.” When the hamzah is added it becomes transitive, as in asbaghtu al-wuḍūʾ (“I perfected the ablution”), i.e., I carried the water to every limb and gave each part its due.
– Umm al-Kitāb: another name for Sūrat al-Fātiḥah, so called because it gathers the great meanings contained in the Quran and because it opens both the recitation and the written text.
– mā tayassara mina l-Qurʾān (“whatever is easy for you of the Quran”): what is meant here is Sūrat al-Fātiḥah, since it is the easiest chapter to memorize, as indicated by the wording in Abū Dāwūd: “then recite Umm al-Kitāb.”
– rākiʿan: rukūʿ is bending the back until the hands reach the knees; its perfection is when the head and the back are level.
– ḥattā taṭmaʾinna rākiʿan (“until you are at ease in bowing”): Some narrations explain ṭumaʾnīnah (calm composure) with the phrases, “until your joints settle and relax,” “until you sit upright,” “so straighten your spine until the bones return,” and, concerning prostration, “he should prostrate until he firmly places his face and forehead.” These statements clarify what ṭumaʾnīnah means in these pillars and similar ones. The preposition ḥattā here marks the limit at which the pillar is fulfilled, indicating that ṭumaʾnīnah is an integral part of it.
– rākiʿan: in the accusative, functioning as an emphatic circumstantial qualifier.
– aqim ṣulbak (“straighten your spine”): with ḍammah on the ṣād and a still lām, though the lām may also be read with ḍammah by analogy. The ṣulb is the vertebral column. The Exalted says: “Emerging from between the backbone and the ribs” (Quran 86:7).