Old Dogen sounds pretty critical here about some other Buddhist practices, such as chanting Nembutsu (chants of praise to a Buddha) and reading Sutras.
In fact, he is against anything that neglects Zazen.
Q: Such reasons as correct transmission by the unexcelled method of the Tathagatas and following in the footsteps of the patriarchs are beyond common sense. To ordinary people, reading the sutras and [chanting] the Nembutsu are the natural means to enlightenment. You just sit cross-legged and do nothing. How is this a means to enlightenment?
A: You look on the meditation of the Buddhas and the supreme law as just sitting and doing nothing. You disparage Mahayana Buddhism. Your delusion is deep; you are like someone in the middle of the ocean crying out for water. Fortunately we are already sitting at ease in the self-joyous meditation of the Buddhas. Isn't this a great boon? What a pity that your true-eye remains shut-that your mind remains drunk. The world of the Buddhas eludes ordinary thinking and consciousness. It cannot be known by disbelief and inferior knowledge. To enter one must have right belief. The disbeliever, even if taught, has trouble grasping it. For example, when the Buddha was preaching at Grdhrakuta, the disbelievers were allowed to go away. To bring out the right belief in your mind you must train and study. If you cannot do this, you should quit for awhile, regretting that you lack the influence of the law from a former beneficial relation. What good are such actions as reading the sutras and saying the Nembutsu. How futile to think that Buddhist merits accrue from merely moving the tongue and raising the voice. If you think this covers Buddhism, you are far from the truth. Your only purpose in reading the sutras should be to learn thoroughly that the Buddha taught the rules of gradual and sudden training and that by practicing his teachings you can obtain enlightenment. You should not read the sutras merely to pretend to wisdom through vain intellections. To strive for the goal of Buddhism by reading many sutras is like pointing the hill to the north and heading south. It is like putting a square peg in a round hole. While you look at words and phrases, the path of your training remains dark. This is as worthless as a doctor who forgets his prescription. Constant repetition of the Nembutsu is also worthless-like a frog in a spring field croaking night and day. Those deluded by fame and fortune, find it especially difficult to abandon the nembutsu. Bound by deep roots to a profit-seeking mind, they existed in ages past, and they exist today. They are to be pitied. Understand only this: if enlightened Zen masters and their earnest disciples correctly transmit the supreme law of the seven Buddhas, its essence emerges, and it can be experienced. Those who merely study the letters of the sutras cannot know this. So put a stop to this doubt and delusion. Follow the teachings of a real master and, by zazen; attain to the self-joyous samadhi of the Buddhas.
From: Bendowa - in 'The Soto Approach to Zen' - by Masunaga Reiho