SB 10.58.45
evam samayam akarnya
baddhva parikaram prabhuh
atmanam saptadha krtva
nyagrhnal lilayaiva tan
Translation:
Upon hearing these terms, the Lord tightened His clothing, expanded Himself into seven forms and easily subdued the bulls.
Purport:
According to Srila Sridhara Svami, Lord Krsna expanded Himself into seven forms not only to playfully defeat the seven bulls but also to show Princess Satya that she would not have to compete with His other queens, since He could enjoy with all of them simultaneously.