Call upon Allah while being certain of being answered
Abu Hurairah, may Allah be pleased with him, narrated that the Messenger of Allah (may the peace and blessings of Allah be upon him) said:
“Call upon Allah while being certain of being answered, and know that Allah does not respond to a supplication from the heart of the heedless one who is occupied by play.”
Certainty in Allah – the Blessed and Exalted - is the highest degree of Ihsan. The one who firmly believes in Allah will submit to him, continue to rely upon him, hope for his mercy and will not stop supplicating him during the night or the day.
The Messenger of Allah – may the peace and blessings of Allah be upon him - is the first of people to surrender to Allah, the best of them in terms of hoping in the mercy of Allah and supplicating him. He teaches his companions to be heedful when they supplicate Allah the Almighty as well as having good expectations in his bounty and being certain that he will respond to them when they urgently supplicate him. He admonished them saying " Call upon Allah while being certain of being answered." Do not doubt, even for a moment, in the response of the supplication, as long as you supplicate Allah out of fear and hope, on the condition that you have purified your hearts of all that disturbs your faith in your Lord, obeyed him as much as you can, earned from lawful sources, began your supplication with the praise and compliment that befit to the Almighty. All of these are relevant to the certainty in Allah.