In Chinese and especially Japanese Buddhism, the statement 天上天下唯我独尊 (Japanese tenjou tenge yui ga dokuson; not sure about the Chinese transliteration), which is typically translated as "On heaven and earth, I alone am honored", is considered to be a well-known statement of the Buddha, spoken when the Buddha first emerged from his mother's womb. The quote is sometimes truncated to just the latter half 唯我独尊 "I alone am honored".
I have done a fair bit of searching for a Sanskrit/Prakrit source from which this quote could have been translated into Chinese, but have had no success so far. What text serves as the origin of this quotation? Did it only first appear after the spread of Buddhism into China?