Allah, the Exalted, says:
"And your Rubb said: `Invoke Me, [i.e., believe in My Oneness (Islamic Monotheism)] (and ask Me for anything) I will respond to your (invocation).''' (40:60)
"Invoke your Rubb with humility and in secret. He likes not the aggressors.'' (7:55)
"And when My slaves ask you (O Muhammad (PBUH)) concerning Me, then (answer them), I am indeed near (to them by My Knowledge). I respond to the invocations of the supplicant when he calls on Me (without any mediator or intercessor).'' (2:186)
"Is not He (better than your gods) Who responds to the distressed one, when he calls on Him, and Who removes the evil?'' (27:62)
An-Nu`man bin Bashir (May Allah be pleased with them) reported: The Prophet (PBUH) said, "Du`a (supplication) is worship.''[Abu Dawud].
Anas (May Allah be pleased with him) reported: The supplication most often recited by the Prophet (PBUH) was: "Allahumma atina fid-dunya hasanatan, wa fil-akhirati hasanatan, wa qina `adhab-annar (O our Rubb! give us in this world that which is good and in the Hereafter that which is good, and save us from the punishment of the Fire).'''[Al-Bukhari and Muslim].
Tariq bin Ashyam (May Allah be pleased with him) reported: Whenever a man entered the fold of Islam, the Prophet (PBUH) would show him how to perform Salat and then direct him to supplicate: "Allahumm-aghfir li, warhamni, wa-hdini, wa `afini, warzuqni (O Allah! Forgive me, have mercy on me, guide me, guard me against harm and provide me with sustenance and salvation).'''[Muslim].
In another narration Tariq said: A man came to the Prophet (PBUH) and said to him: "O Messenger of Allah! What shall I say if I want to pray to my Rubb?'' He (PBUH) said, "Say: `Allahumma-ghfir li, warhamni, wa `afini, warzuqni (O Allah! Forgive me, have mercy on me, protect me and provide me with sustenance).' Surely, this supplication is better for you in this life and in the Hereafter.''
`Abdullah bin `Amr bin Al-`As (May Allah be pleased with them) reported: The Messenger of Allah (PBUH) supplicated: "Allahumma musarrifal-qulubi, sarrif qulubana `ala ta`atika (O Allah! Controller of the hearts, direct our hearts to Your obedience).
Abu Hurairah (May Allah be pleased with him) reported: The Messenger of Allah (PBUH) used to say: "Allahumm-aslih li diniyalladhi huwa `ismatu amri, wa aslih li dunyaya-llati fiha ma`ashi, wa aslih li akhirati-llati fiha ma`adi, waj`alil-hayata ziyadatan li fi kulli khair, waj`alil-mauta rahatan li min kulli sharrin (O Allah, make my religion easy for me by virtue of which my affairs are protected, set right for me my world where my life exists, make good for me my Hereafter which is my resort to which I have to return, and make my life prone to perform all types of good, and make death a comfort for me from every evil).''
[Muslim].
Abu Bakr As-Siddiq (May Allah be pleased with him) reported: I requested the Messenger of Allah (PBUH) to teach me a supplication which I could recite in my Salat (prayer). Thereupon he said, "Recite: `Allahumma inni zalamtu nafsi zulman kathiran, wa la yaghfirudh-dhunuba illa Anta, faghfir li maghfiratan min `indika, warhamni, innaka Antal-Ghafur-ur-Rahim (O Allah! I have considerably wronged myself. There is none to forgive the sins but You. So grant me pardon and have mercy on me. You are the Most Forgiving, the Most Compassionate).'''
[Al-Bukhari and Muslim].
