Is the remembrance or glorification between the rak'ahs of Qiyam (standing prayer) saying: "Subhanaka Rabbana wa bihamdika, Allahumma Ighfir Lana (Glory be to You, our Lord, and with Your praise, O Allah, forgive us)" considered an innovation (bid'ah)?

The Prophet (peace be upon him) frequently recited: "Glorified are You, O Allah, our Lord, and with Your praise, O Allah, forgive me" during his bowing (ruku') and prostration (sujud), interpreting the Qur'an. There is no objection to using this supplication between the rak'ahs of the Qiyam prayer, but it should not be believed that it is a prescribed Sunnah that must be continuously observed, due to the absence of any textual evidence supporting this.