The Difference Between Adding to the Pillars and Adding to the Voluntary Acts

The questioner : But the non-prescription of adding to four is like the non-prescription of adding to "no," if we take the roots.

The Shaykh : No, no, it is not like it, no, it is not like it. And therefore, if one adds to the two rak'ahs according to those who say it is obligatory, many of them say: do not accept the prayer, but he becomes sinful.