The Interdependence of Faith and Supplication in Attaining Guidance: A Quranic Exposition of Surah Al-Baqarah 2:186
And when My servants ask you about Me, (say) I am close (to them), when the supplicant calls upon Me, I accept his supplication, so they should also respond to My invitation. And believe in me that they may be on the right path.
Surah Baqarah verse 186
He is closer to the believer's heart than his jugular vein. There is no barrier to reaching Him except one's own self. No material means are required to reach Him; one can approach Him directly. The promise in this verse is: 'I respond to the invocation of the supplicant when he calls Me.' The condition is: 'So let them respond to Me [by obedience] and believe in Me.' If one fulfills the condition of calling upon Allah with sincerity and devotion, then Allah does not go against His promise. According to the traditions, prayer is a believer's weapon, the essence of worship, the key to success, the best form of worship, and a believer's shield. For the acceptance of prayers, divine recognition, actions in accordance with His commandments, earning through halal means, and having a present heart are essential. Even in times of ease, one should continue to pray with humility and supplication. Through prayer, a person becomes worthy of divine mercy and becomes deserving of Allah's intentions, thereby changing his fate. It is narrated from Imam Ja'far as-Sadiq (ع): 'Prayer repels the decree that has been set, even after it has been set.'
Al-Mustadrak 116:5
Prayer can change destiny even after a decisive stage has been reached. The etiquette of prayer is to first praise and glorify Allah, then send blessings upon Muhammad and his family, and confess one's sins."