Thus I have heard. Those words are the first of the Six Requirements. It is essential that all who lecture or read sutras be quite familiar with the Six Requirements which are: belief, hearing, time, host, place and audience.

1. Thus is the requirement of belief,

2. I have heard is the requirement of hearing,

3. At one time is the requirement of time,

4. The Buddha is the requirement of a host,

5. In Sravasti in the Jeta Grove of the Garden of the Benefactor of Orphans and the Solitary is the requirement of a place,

6. Together with a gathering of great bhikṣus, twelve hundred fifty in all is the requirement of an audience.

The six requirements prove that a sutra was spoken by the Buddha. Since the requirements begin every sutra, they are called the “Common Preface.” The text which immediately follows them varies with each sutra, and so it is called the “Specific Preface.” In this sutra the Specific Preface is:

“At that time, at mealtime, the World Honored One put on his robe, took up his bowl, and entered the great city of Sravasti to beg for food. After he had finished his sequential begging within the city, he returned, ate the food, put away his robe and bowl, washed his feet, arranged his seat, and sat down.”

The Common Preface is also called both the “Foreword” and the “Postscript.” When lecturing sutras one can discuss this section as a foreword to the sutra and also as a postscript appended at a later date….

The six requirements are called the Postscript because they were not part of the original sutra. The Buddha did not say “Thus I have heard…” That text was added afterwards by the Venerable Ananda when the sutra division was compiled. The Postscript is also called the Prologue. Therefore the six requirements may be called the Foreword, the Prologue, and the Postscript.

The Buddha Instructed that all sutras he spoke should begin with the four words “Thus I have heard…” Those who investigate Buddhist sutras should know the history of those four words.