(Bismillaahir Rahmaanir Raheem)
Allâh, the Mighty, said:
وَقَالَ رَبُّكُمُ ٱدۡعُونِيٓ أَسۡتَجِبۡ لَكُمۡۚ إِنَّ ٱلَّذِينَ يَسۡتَكۡبِرُونَ عَنۡ عِبَادَتِي سَيَدۡخُلُونَ جَهَنَّمَ دَاخِرِينَ
"And your Lord said: "Invoke Me, I will respond to your (invocation). Verily! Those who scorn My Worship [i.e. do not invoke Me, and do not believe in My Oneness, (Islâmic Monotheism)] they will surely enter Hell In humiliation!" (Al-Ghâfir: 60).
وَإِذَا سَأَلَكَ عِبَادِي عَنِّي فَإِنِّي قَرِيبٌۖ أُجِيبُ دَعۡوَةَ ٱلدَّاعِ إِذَا دَعَانِۖ فَلۡيَسۡتَجِيبُواْ لِي وَلۡيُؤۡمِنُواْ بِي لَعَلَّهُمۡ يَرۡشُدُونَ
"And when My slaves ask you (O Muhammad) concerning Me, then (say), I am indeed Near (to them by My Knowledge). I respond to the invocations of the supplicant whenever He calls on Me (without any mediator or intercessor). So let them obey Me and believe in Me, so that they may be led aright." (Al-Baqarah: 186).
The Prophet - salallaahu alahyi wa sallam - said: ‘Supplication is worship, your Lord has said:
ٱدۡعُونِيٓ أَسۡتَجِبۡ لَكُمۡۚ
“Invoke Me, I will respond to your (invocation).” (Al-Ghâfir: 60).
[Abū Dâwud 2/78, At-Tirmidhî 5/211 and Ibn Mâjah 2/1258. See Al-Albâni's Sahîh Jāmi’s-Saghīr 3/150 and Sahîh Ibn Mâjah 2/324]
He - salallaahu alahyi wa sallam - also said: ‘Surely, your Lord – the Blessed and Exalted – is Bashful; He feels shy from His slave when he raises his hands in supplication that he returns them empty.’
[Abū Dâwud 2/78, At-Tirmidhî 5/557 and Ibn Mâjah 2/1281. Ibn Hajar said: ‘It’s chain is good.’ See Sahîh At-Tirimidhi 3/179]
He - salallaahu alahyi wa sallam - also said: ‘No Muslim will invoke Allâh with such an invocation that does not contain sin or severance of kinship except that Allâh grants him his requests in one of (these) three ways: He may respond to his call immediately; He may preserve (the reward of prayer) for him in the Hereafter or that He averts an evil for him the like thereof.’
They said: ‘Therefore, we shall be making much supplications.'
He - salallaahu alahyi wa sallam - said: ‘Allâh will grant them the more.’
[Abū Dâwud 2/78, At-Tirmidhî 5/557 and Ibn Mâjah 2/1281. Ibn Hajar said: It is chain is good. See Sahîh At-Tirimidhi 3/179]
Source: Sa'îd b. Wahf Al-Qahtânî’s Invocations from Qur'ân and Sunnah, Translated by Aboo Aamir Ishaaq b. AbdirRaheem for an international Islamic publishing house.