Śūraṅgama Sūtra, Volume Seven: Original Text

于初七中，至诚顶礼十方如来，诸大菩萨，阿罗汉号。恒于六时诵咒围坛，至心行道。一时常行一百八遍。第二七中，一向专心发菩萨愿，心无间断。我毗奈耶先有愿教。第三七中，于十二时，一向持佛般怛啰咒。至第七日，十方如来一时出现。镜交光处，承佛摩顶。即于道场修三摩地。能令如是末世修学，身心明净犹如琉璃。阿难。若此比丘本受戒师，及同会中十比丘等，其中有一不清净者，如是道场多不成就。从三七后，端坐安居，经一百日。有利根者，不起于座，得须陀洹。纵其身心圣果未成。决定自知成佛不谬。汝问道场，建立如是。 

Explanation of the above:

1. The Śūraṅgama Mantra is especially supreme; everyone should be able to recite it from memory, persisting daily in reciting it seven to one hundred and eight times.

2. Making vows is especially important. Sustained by the power of vows, nothing is unconquerable. If you wish to attain accomplishment in learning Buddhism, if you wish to resolve the great problem of birth and death, you must learn from the Buddha to make great vows, to protect and uphold the Buddhadharma and Buddhism, benefiting both yourself and others. Without the pull of vow-power, cultivation is slower than an old ox. Among those who have achieved accomplishment in cultivation, there is not a single one who was not pulled along by the power of vows; without vow-power, one is pulled along by the power of karma. Without making vows, the compassionate mind cannot arise. When pulled by the power of vows, the mind becomes firm and one is unafraid of hardship. After making vows, one's aspirations will gradually be fulfilled. 

3. Strictly practicing the above two points within the altar arena—reciting the Śūraṅgama Mantra and making vows while prostrating to the Buddha—one will surely enter samādhi and receive the Buddha's touch on the crown of the head. 

4. If the precept-transmitting master's body and mind are not pure, the precepts received by the precept recipient will not be pure. If the bhikṣu presiding over the practice arena has an impure body and mind, the arena will also not be accomplished, and cultivating within such an arena will be of no benefit. Therefore, first, everyone should receive the precepts as soon as possible; second, one should examine whether the precept-transmitting master has a pure mind; third, one should investigate whether the abbot of the practice arena where one cultivates has a pure body and mind. 

Here the Buddha tells us that in cultivation we must choose a precept-transmitting master and a monastic master to follow who have good and pure minds, and also choose a practice arena whose abbot has a pure mind. If you have previously received the precepts, you should examine whether you obtained the precept substance (śīla-saṃbhāra); if you suspect you did not obtain the precept substance, it is best to purify your karmic offenses through repentance, and then once again choose a pure precept-transmitting master to receive the precepts. 

The Buddha taught us in the Śūraṅgama Sūtra that if one establishes an altar arena, during the third seven-day period, for twenty-four hours each day one should exclusively recite the Śūraṅgama Mantra one hundred and eight times, and then the Buddha will come to touch one's crown in reassurance, and one will enter samādhi. Thereafter, during one hundred days of dwelling in peace and sitting quietly, unmoving and unshaken, one will realize the first fruit of srotāpanna. Nowadays, to establish an altar arena—a pure practice arena—it seems one can no longer find ten bhikṣus with pure minds; and the ten masters who transmit the three platforms of great precepts at precept arenas are not all pure either, so whether a monastic's precept substance can be accomplished is hard to say. If we do not cultivate diligently in this life, who knows when in a future life we might obtain a human body and encounter the Buddhadharma; and even if we do encounter the Buddhadharma, what the Buddhadharma will have become by then is truly hard to say. Observing the suffering of beings in the three evil destinies now, we know that when we ourselves go to the three evil destinies in the future, it will be the same—not much different. Everyone truly has no reason to waste time and be irresponsible toward their own future.