Ruling and evidence on Tajwid of Qur'an recitation in Salah

Q 2: Is following the rules of reciting the Qur'an obligatory during Salah (prayer)? What is the evidence for that?

A: Allah (Glorified and Exalted be He) orders us to recite the Qur'an and to give every letter its due right. Allah says: And recite the Qur’ân (aloud) in a slow, (pleasant tone and) style. The Prophet (peace be upon him) used to recite the Qur'an in a slow style and pleasant tone by giving every letter its due right as if saying it alone. He also used to pause after every Ayah (verse) and prolong his voice in the letters that should be prolonged. He used to prolong the word "Al-Rahman" (the Merciful) and "Al-Rahim" (the Compassionate). Moreover, he used to seek refuge in Allah against the accursed devil at the beginning of his recitation.May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.