Upali, one of the ten main disciples of the Buddha, was noted for his understanding of the monastic law and discipline (Vinaya). He is said to have recited the code of rules from memory at the First Council held at Rajagrha.
The taking of vows and receiving of precepts is an essential part of the tantric or vajrayana path. His Holiness Dorje Chang Buddha III has told us that in the Buddha-dharma, there are the principles of faith, vows, and special tantric practices as well as the principles of morality, concentration and wisdom that are also followed in exoteric Buddhism. All of these must be kept in mind. One must first vow to abide by the precepts. If one observes the precepts, one will not make mistakes. Making vows is something very complicated. There are the ordinary oral vows one makes that one will do a certain thing. There is also the kind of vow made in front of the buddhas and bodhisattvas. If this type of vow is not fulfilled, then one must receive serious karmic retribution. There are different types of precepts, such as the Three Pure Comprehensive or Cumulative Precepts, the Five Precepts, the Samaya Precepts, the Vinaya Precepts (for bhikshus and bhikshunis), the Bodhisattva Precepts, the Ten Shramanera Precepts, the Special-Tantric Precepts, the Inner-Tantric Precepts and the Secret-Tantric Precepts. You can also violate precepts relating to your Master. If you do not abide by the precepts, you will not attain concentration. The buddhas and bodhisattvas gave us a wonderful method to overcome these problems—namely abiding by the precepts. The precepts represent a mandatory Dharma practice. Mandatory Dharma is directed against the negative habitual conduct of living beings which is deeply ingrained. You must practice them. It does not matter whether you want to practice them or not. It is futile to receive any precepts if you have not resolved to strictly abide by them. Your master will transmit different precepts to you based upon your past karma and what you need to do obtain enlightenment. The master must also abide by strict rules in transmitting appropriate precepts and not be overly lenient, act carelessly, or misjudge you based on affection or fear of hurting your feelings, resulting in the premature transmission of precepts. Those who cultivate themselves and learn Buddhism cannot violate the precepts received. Minor violations will result in negative karmic retribution. Major violations will cause one to descend into hell. If your master does not give you certain precepts, it is out of concern that you are not yet ready to receive them. Your master does not want you to incur negative karmic retribution if he or she can foresee that you will violate the precepts. It is futile to be initiated into any of the five inner-tantra initiations when you do not abide by the samaya precepts. No matter how great the merit and supernormal powers of the master conferring the initiation or the communications established with the buddhas, yidams, dharma protectors, etc. during the initiation, if you do not abide by these rules it will all be in vain. If you violate the samaya precepts, you must sincerely and deeply repent. Otherwise, you will degenerate. Once these precepts are violated, it will be impossible to attain any accomplishment. Whoever violates such precepts must bear the karmic responsibility. Unless you repent and sincerely correct your errors, no matter how energetically you practice, your practice will be futile.The making of vows and the taking of precepts must be done with your Vajra Master. The esoteric vows and precepts are taken in conjunction with the various tantra initiations. They are not discussed with anyone who has not received the appropriate initiation.
Sakya Pandita Kunga Gyaltshen’s A Clear Differentiation of the Codes: Essential Distinctions Among the Individual Liberation, Great Vehicle, and Tantric Systems; Jamgon Kongtrul’s Buddhist Ethics; and Dudjom Rinpoche’s Perfect Conduct: Ascertaining the Three Vows are books available through the Xuanfa Bookstore that explain and compare the vows taken at various stages of the path.