Mu’aaz رَضِىَ الـلّٰـهُ عَـنْهُ was familiar with the language of the non-Muslims. Heرَضِىَ الـلّٰـهُ عَـنْهُ   once heard them say this word and said: ‘O enemies of Allah! May the curse of Allah be upon you! If I hear this word from anyone’s tongue again, I will sever his neck.’

The non-Muslims said: ‘You are angry at us, but the Muslims also use this word.’

He رَضِىَ الـلّٰـهُ عَـنْهُ became upset at this and came to the Beloved Prophet صَلَّى الـلّٰـهُ عَلَيْهِ وَاٰلِهٖ وَسَلَّم. He رَضِىَ الـلّٰـهُ عَـنْهُ had just arrived in the court of the Holy Prophet صَلَّى الـلّٰـهُ عَلَيْهِ وَاٰلِهٖ وَسَلَّم and the verse was revealed in which it was prohibited to say ‘رَاعِنَا’, and the command to use another synonym of it, ‘اُنۡظُرْنَا’, was given. (Qurtubi, Surah Al-Baqarah, Taht-al-Ayah 104, vol. 1, pp. 44-45; Tafseer Kabeer, Surah Al-Baqarah, Taht-al-Ayah 104, vol. 1, p. 634; Tafseer ‘Azeezi, vol. 2, p. 669, selected)

Hence, it is stated in part 1, Surah Al-Baqarah, verse no. 104:

یٰۤاَیُّهَا الَّذِیْنَ اٰمَنُوْا لَا تَقُوْلُوْا رَاعِنَا وَ قُوْلُوا انْظُرْنَا وَ اسْمَعُوْاؕ-

O believers! Do not say (to the Prophet Muhammad), ‘Raa’ina,’ and submit as so; ‘Unzurna (meaning that please grant us your attention so that we understand well), and (O Muslims) listen attentively (to his discourse) from the beginning.’

[Kanz-ul-Iman (translation of Quran)] (Part 1, Surah Al-Baqarah, Verse 104)

Under this verse, it is stated in Tafseer Siraat-ul-Jinaan:

   ۔1To respect and honour the Noble Prophets عَـلَـيْهِمُ السَّلَام, and to maintain due etiquette in their courts is Fard, and it is prohibited to use the word in which there is the slightest possibility of disrespect.