Khandogya-Upanishad: Seventh Prapathaka, Twenty-Sixth Khanda
2. “There is this verse,
He who sees this, does not see death,
nor illness, nor pain;
He who sees this, sees everything,
and obtains everything everywhere.
He is one (before creation), he becomes three (fire, water, earth), he becomes five, he becomes seven, he becomes nine; Then again he is called the eleventh, and hundred and ten, and one thousand and twenty.
“When the intellectual aliment has been purified, the whole nature becomes purified. When the whole nature has been purified, the memory becomes firm. And when the memory (of the Highest Self) remains firm, then all the ties (which bind us to a belief in anything but the Self are loosened.
“The venerable Sanatkumara showed to Narada, after his faults had been rubbed out, the other side of darkness. They call Sanatkumara Skanda, yea, Skanda they call him.”