What is the ruling on the opening takbir (Allahu Akbar) and raising the hands, and how should they be raised? What is the ruling on one who throws his hands from in front of his belly or plays with his shemagh after the takbir? Is extending the hands before grasping (for qiyam) obligatory?

The opening takbir (Allahu Akbar) is a pillar without which the prayer is invalid. Raising the hands during it is a Sunnah (definition) by consensus. It is also recommended to raise them when performing the takbir for bowing and when rising from it. The hands should be raised parallel to the shoulders, such that the fingertips are level with the earlobes, the thumbs with the fleshy part of the ears, and the palms with the shoulders. Playing with one's turban or similar items during prayer is an act of futility that contradicts tranquility. It is not obligatory to let the hands hang down before grasping them after the opening takbir; rather, it is better to place them under the chest.