佛祖統紀 34.33

34.33

The first is the Avataṃsaka period. At the bodhimaṇḍa, he initially spoke the Avataṃsaka. During three times seven days, he contemplated such matters. This refers to the Tathāgata's initial preaching of the sudden [teaching]. In terms of the text, it is sudden; in terms of the teaching, it combines the distinct with the perfect. It is like the sun first rising and first shining on the high mountains. Furthermore, it corresponds to drawing milk from a cow (the preaching during the three times seven days is called the Avataṃsaka of the Quiescent Site).