Udana 1.3

Thus have I heard. On a certain occasion the Exalted One, soon after the attainment of Buddhahood, dwelt at Uruvela on the banks of the stream Neranjara, at the foot of the tree of Enlightenment. At that time the Exalted One, after remaining in a sitting posture for seven days, experienced the bliss of Emancipation. 

When the seven days had come to a close, the Exalted One arose from the state of trance and in the last watch of the night thoroughly thought out the chain of cause and effect in both the direct and indirect orders. 

Now by the complete destruction of Ignorance, there is cessation of Conformations. And the Exalted One in this connection, on that occasion, breathed forth this solemn utterance: 

"When the conditions of existence dawn upon the strenuous, meditative Brahmana, 

He stands, scattering the hosts of the Tempter, as the Sun, diffusing its rays through space."