Is it permissible to extend the transitional تكبيرة (Allahu Akbar) to include the sitting for rest (جلسة الاستراحة) with the intention of being engrossed in prayer through remembrance (dhikr), and is this action considered a bid'ah (innovation)?

Some jurists are of the opinion that the takbir (proclamation of 'Allahu Akbar') in the sitting of rest begins from raising the head from prostration and extends until one stands upright. This is the soundest view among the Shafi'is. Imam An-Nawawi, in Al-Majmu', mentioned three views regarding the takbir: the soundest of them is to begin the takbir when raising the head from prostration and to extend it until one stands upright, so that no part of the prayer is devoid of remembrance. Therefore, there is no objection to doing what was asked about.