It seems that the first ones who said “Karrama Allaah wahjahu” (may Allaah honour his face) concerning ‘Ali ibn Abi Taalib (may Allaah be pleased with him) were the Shi’ah, and some of the scribes who took this from the Shi’ah.
1 – Imam Ibn Katheer (may Allaah have mercy on him) said:
I say: it is very common among many of the scribes who copy out books to write ‘alayhi’l-salaam (peace be upon him) after the name of ‘Ali (may Allaah be pleased with him) but not after the names of other Sahaabah, or to write karrama Allaah wajhahu. Even though the meaning is acceptable, all the Sahaabah should be treated with the same respect. The two Shaykhs (i.e., Abu Bakr and ‘Umar) and ‘Uthmaan are more deserving of that, may Allaah be pleased with them.
Tafseer Ibn Katheer, 3/517-518
2 – The Standing Committee said:
Saying karrama Allaahu wajhahu after the name of ‘Ali and singling him out for that is part of the exaggeration of the Shi’ah concerning him. And it was said that this is because he never saw the ‘awrah of another person, or because he never prostrated to any idol.
But this does not apply only to him; it applies also to other Sahaabah who were born in Islam.
And Allaah knows best.