Natyashastra
अपदान्यनिबद्धानि तालेन रहितानि तु । आतोद्येषु नियुक्तानि तानि तानि तु रञ्जयेत् ॥ ३३॥
Those Padas which are irregularly composed and devoid of time-measure (tāla) are employed in connection with the musical instruments, and they serve to embellish and delight them.
english translation
apadAnyanibaddhAni tAlena rahitAni tu । AtodyeSu niyuktAni tAni tAni tu raJjayet ॥ 33॥
hk transliteration by Sanscript