The opening takbir is the obligatory act by which one enters the prayer, whereas raising the hands at the opening is a Sunnah, not an independent fard or wajib.
If the formula is pronounced but the hands are not raised, the opening obligation is performed but this Sunnah movement has been omitted.
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Description of Prayer: Opening Takbir, Raising Hands, Hand Placement and Thana
The opening takbir is the obligatory act by which one enters the prayer, whereas raising the hands at the opening is a Sunnah, not an independent fard or wajib.
If the formula is pronounced but the hands are not raised, the opening obligation is performed but this Sunnah movement has been omitted.