St Demetrius of Rostov (September 21), in his Discourse on the Day of Appearance of the Icon of the Mother of God at Kazan (July 8), said:
“The Mother of God delivered from misfortune and woe not only the righteous, but also sinners, but which sinners? those who turn themselves to the Heavenly Father like the Prodigal Son, they make lamentation beating their bosom, like the Publican, they weep at the feet of Christ, like the Sinful Woman washing His feet with her tears, and they offer forth confession of Him, like the Thief upon the Cross. It is such sinners whom the All-Pure Mother of God heeds and hastens to aid, delivering them from great misfortunes and woe.”
Knowing that they suffered such misfortunes for their sins, the whole nation and the army imposed upon themselves a three-day fast. With prayer, they turned to the Lord and His All-Pure Mother for help. The prayer was heard. St Sergius of Radonezh appeared to St Arsenius (afterwards Bishop of Suzdal) and said that if Moscow were to be saved, then people must pray to the Most Holy Virgin. Emboldened by the news, Russian forces on October 22, 1612 liberated Moscow from the Polish usurpers. A celebration in honor of the Kazan Icon of the Most Holy Theotokos was established in 1649. Even in our own day this icon is especially revered by the Russian Orthodox nation.
The Kazan Icon is also commemorated on July 8.