Is it obligatory for the worshiper to add to the glorification in bowing or prostration if he has not first contemplated its meaning, and will there be any consequence if he does not do so?

The worshipper's humility (khushu') and contemplation of what he recites and says in his bowing (ruku') and prostration (sujud) are required. Abandoning this deprives him of reward but does not invalidate his prayer, according to the sounder opinion. If one feels during bowing or prostration that he was not humble, and then prolongs his bowing or prostration and achieves humility therein, this is good. Even if he does not do so, his prayer is valid, though its reward is diminished.