This is not in contradiction to what we have previously mentioned, because what He عليه السلام, peace be upon him, intended was the case where a person has completed standing in the fourth rak’ah and does not know whether he bowed in the third or not, then, in such a situation, he must continue with his prayer. This falls under the second category we previously explained, namely: if one doubts about the bowing after having entered into another position, he continues with his prayer. What confirms what we have said is:
Commentary #14