Benefits of the Hadith of Anas.

The Shaykh : In this is evidence for arguing by negation or absence, based on his statement: This is evidence that if the cause for an action is present but the action is not performed, that serves as evidence of its absence. So if someone were to say, "Perhaps he turned his cloak," what would we say? We would say, if he had turned it, he would have mentioned it. Likewise, if he had stood up facing the qiblah, we would say, if he had faced the qiblah, he would have mentioned that he turned and faced the qiblah. Thus, arguing by absence is valid when the situation necessitates mentioning it and he did not mention it. This qualifies what was said about the absence of mention not being a mention of absence; rather, we say that if the situation necessitates mention and he did not mention it, then it is a mention of absence.