What is the ruling on praying quickly?

Tranquility (طمأنينة) in prayer is a pillar without which the prayer is invalid. The evidence for this is the hadith of the one who prayed badly, in which the Prophet, peace and blessings be upon him, said: "When you stand for prayer, say the Takbir (Allahu Akbar), then recite what is easy for you from the Qur'an, then bow until you are at ease while bowing, then rise until you are at ease while standing, then prostrate until you are at ease while prostrating, then rise until you are at ease while sitting, and do that throughout your entire prayer." This is the view of the majority of scholars. If the speed in prayer compromises tranquility, then the prayer is invalid. If it does not compromise it, then the prayer is valid. The definition of tranquility is the settling of the limbs in the posture of the pillar.