Praise be to Allah the Lord of the Worlds. May His peace and blessings be upon our Prophet Mohammad and upon all his family and companions.

Upon hearing the verse: "Will not the Unbelievers have been paid back for what they did?" {Al-Mutaffifin, 36}, while performing prayer or not, it is recommended for the person, to say, for example, yea, this is Allah`s justice and wisdom.

This wasn`t mentioned in the Prophetic Sunnah, however, jurists stated that when a person hears the Quran, while praying or not, they should ponder upon it, deeply think about it, and respond to that verbally following the Sunnah of the Prophet (Peace and blessings be upon him). Hudhaifah (May Allah be pleased with him) reported: I performed Salat with the Prophet (Peace be upon him) one night, and he started reciting Surat Al- Baqarah……………………..He recited leisurely. When he recited an Ayah which mentioned the tasbeeh, he would say Subhan Allah and when he recited the Ayah which tells how the Rubb is to be asked, the Messenger of Allah (Peace be upon him) would then ask from Him; and when he (Peace be upon him) recited an Ayah asking one to seek Protection Allah, he would seek Protection of Allah. Then he bowed and said, "Subhana Rabbiyal-Azim (My Rubb the Great is free from imperfection)"; his bowing lasted about the same length of time as his standing, (and then on returning to the standing posture after Ruku') he would say, "Sami' Allahu liman hamidah, Rabbana lakal-hamd (Allah listens to him who praises Him. Praise be to You, Our Rubb!)," and he would then stand about the same length of time as he had spent in bowing. He would then prostrate himself and say, "Subhana Rabbiyal-A'la (My Rubb the Supreme is free from imperfection)," and his prostration lasted nearly the same length of time as his standing (Qiyam). [Muslim].

Al-Shirbini says, "When a person, while praying or not, recites a verse in which mercy is mentioned, it is recommended that he seeks Allah`s mercy. When he recites a verse in which punishment is mentioned, it is recommended that he seeks refuge in Allah from His punishment. When he  recites a verse in which a supplication is mentioned, it is recommended that he glorifies Allah. If he recites (Is not Allah the most conclusive of all judges ? ) {At-teen, 8}, it is recommended that he says yea, and I bear witness to that. If he recites (In what fact after this will they believe ?) {Al-`Araf, 185}, it is recommended that he says, I do believe in Allah. If he recites (who then could bring you gushing water ?) {Al-Mulk, 30}, it is recommended that he says, Allah the Lord of the Worlds." {Moghni al-Mohtaj}.

In addition, there are other views regarding the verse mentioned in the above question. For more details, check out books of Tafseer. And Allah the Almighty knows best.