the following two verses are the basis for the deposition that abrogation in the Quran did occur
I would like to comment on a fundamental difference between the two verses;
the abrogation verse:
and the substitution verse:
In 16:101, God talks about replacing one verse by putting another in its place
, which means that the original verse is gone from the Quranic text. Only in 2:106, where God talks about abrogating one verse by another, is there a possibility
that the original verse is not actually gone, but remains in the Quranic text albeit abrogated.
This distinction is important because the most fundamental question in the issue of abrogation is whether any verse in the text of the Quran (at the time of the death of the Prophet PBUH) is an abrogated verse. The verses that had been revealed, and were later replaced during the life of the Prophet by other verses (with the original verse gone from the text), can be covered by 16:101. However, if a verse survived in the completed text of the Quran, then it was not substituted by another (per 16:101) since the substituting verse would have taken its place.
Therefore, 16:101 is not relevant to the question of whether any verse in the text of the Quran is an abrogated verse. Only 2:106 may be relevant to this question. On the other hand, the larger question of whether any verse that had ever been revealed was later abrogated may relate to both 16:101 or 2:106.
If we only address the question of whether any verse in the text of the Quran is an abrogated verse, then we only need to address 2:106, not 16:101.