Natyashastra
यः समैः संहितो गच्छेत्तत्र कार्यो लयाश्रयः । चतुष्कलोऽथ द्विकलस्तथैवैककलः पुनः ॥ २१॥
When one walks along with equals, the tempo to be followed should be four Kalās, or two Kalās, or one Kalā accordingly.
english translation
yaH samaiH saMhito gacchettatra kAryo layAzrayaH । catuSkalo'tha dvikalastathaivaikakalaH punaH ॥ 21॥
hk transliteration by Sanscript