Dua is defined as any invocation or prayer addressed to Allah (SWT).
We find many reassurances throughout the Quran for those who make Dua. Allah the Exalted, has said: "And your Lord says: Pray unto me: and I will hear your prayer" (Quran 40:60), "Call upon your Lord Humbly and in secret" (Quran 7:55), "When My servants question thee concerning Me, I am indeed close (to them): I listen to the prayer of every suppliant when he calleth on Me" (Quran 2:186), "Is not He (best) who listens to the (soul) distressed when it calls on Him, and who relieves its suffering." (Quran 27:62)
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