A. W. Tozer above all else sought to know God, to really know him, to experience him. (He was doing Blackaby before Blackaby. More accurately, he was doing Philippians 3:7ff.) Hence book titles like The Pursuit of God and The Knowledge of the Holy.
To really know God, Tozer rightly believed that much time needed to be given to prayer. In his biography of Tozer, Lyle Dorsett writes:
"Tozer spent incalculable hours in prayer. Most of his prolonged prayer time--with his Bible and hymnals as his only companions--took place in his church office ... He would ... sit for a while on his ancient office couch. After a time his spirit would drift into another realm. In time, he would abandon the couch, get on his knees, and eventually lie facedown on the floor, singing praises to the Lion of the Tribe of Judah.
"No one presumed to interrupt these times of intimacy between A. W. Tozer and the Lover of his soul. But occasionally one of the men closest to him would climb the steps to his office and chance to see him on the couch or floor--totally oblivious to the world....
Tozer never denied that he spent many hours in prayer out of his increasingly demanding schedule. On the contrary, he maintained that anyone who wanted to know Christ better and love Him more must devote time to closet prayer." (121-122)
Tozer prayed to know Christ, but there were some secondary motives as well. He also prayed in order to guard against the pride that comes with fame, to stay rooted in humility before the majesty of Christ, and to guard against doing ministry in his own strength.
"As the years passed Tozer increased his daily time in Bible reading and prayer--at once meditating on the Scriptures, praising the One who inspired them, seeking God's help in writing words with the power to transform souls, and applying truths to everyday life." (146)
His preaching and his writing were anointed by the Holy Spirit, and they grew out of his prayer life.
Dorsett Cites Tozer's associate pastor in Chicago, Ray McAfee: "His preaching was affected by his praying. Indeed, preaching was a declaration of what he had learned in prayer" (132).
A young seminarian once wrote Tozer to ask him how he did sermon preparation. "Typically, Tozer pointed to the Lord and wrote: 'I get on my knees and manage to get three sermons a week together'" (136).
Tozer once offered further insight into his sermon prep: "I never go to the Bible for a sermon, I go to the Bible to see God. Then I get words for sermons" (135).