How can one get rid of the whispers during prayer that diminish devotion and lessen faith and good deeds?

Among the signs of a servant's righteousness and a heart's vitality is the reviewing of one's states, actions, and thoughts. One should not imagine that the heart's vitality is an easy matter or that it can be attained by any means. Complete tranquility in this world or perfect humility is not possible, and accepting this, seeking reward, is the first step in treatment. Seeking humility, perseverance, and striving are duties, and whoever strives in this will attain a great reward. Despair does not afflict the believing Muslim, for the most important thing is to tread the right path, seek the means of humility, and endure hardship. To treat the absence of the heart during prayer, one must ward off distracting thoughts. This is achieved by recalling the remembrance of the Hereafter and the state of intimate supplication before prayer, and by emptying the heart of distractions. If this is not enough, then one must examine the diverting matters and discipline the self by abandoning desires and severing distracting attachments; for the love of this world prevents the pleasure of intimate supplication, and combining the concerns of this world and the Hereafter is like combining water and vinegar in one vessel.