What is the basis for authenticating the hadith (It is from the Sunnah to conceal the tashahhud), which contains Ibn Ishaq, who used the style of indeterminate attribution and did not explicitly state hearing in the chains of the hadith?

The questioner : The first issue, O Shaykh.

The Shaykh: And in it is Abu Ishaq.

The questioner : Ibn Ishaq, and he did not explicitly state that he heard it.

The Shaykh: Beautifully, may Allah bless you. There is a matter related to fiqh, not to hadith. Therefore, we criticize many of the young students of hadith today who assume that one who has mastered the science of hadith but has not mastered fiqh can authenticate and weaken hadiths. I say that such a person is like a non-Arab who can never master the science of hadith if he is a non-Arab who does not understand the Arabic language. Likewise, I say that a student of knowledge cannot authenticate or weaken hadiths with knowledge unless he is a jurist, because some hadiths are supported in their authentication by fiqh matters, even if they have an apparent defect. Now I will mention two things here. The first thing: If we look away from this hadith and assume that it did not come at all, not with a valid, good, or weak chain, and has no basis whatsoever, if we assume this, the question will arise: What is the Sunnah in the tashahhud? Is it loud or silent? What will be the answer of the jurist?

The questioner : Quiet.

The Shaykh: Where did this come from? From the hadith of Abu Ishaq? No, where did it come from? I do not want to go into where it came from. It is enough for you to know that the one who came with this concealment is the one who strengthened the hadith of Abu Ishaq. Is that clear?

The questioner: Truly.

The Shaykh: And the free man is sufficient with a gesture.