Why was prayer the main pillar of the religion?

Prayer holds a great status in Islam; it is the second pillar after the two testimonies and the first act of a servant to be judged. Whoever preserves it will succeed, and whoever neglects it will fail. It is called the pillar of religion because of the humility it entails before Allah through bowing (rukūʿ) and prostration (sujūd), where a Muslim places their most noble limbs on the ground in exaltation of their Creator. Al-Ghazali said that it contains secrets that made it the pillar of religion, among them humility by standing, bowing, and prostrating. This is a service to Allah that is not achieved by laziness but by diligence and submission.