Natyashastra
निवृत्तौ तु कला न्यूना यदा वस्तुवशाद्भवेत् । अकालपातनात्तस्या वर्णः कार्यो निवृत्तिमान् ॥ १२३॥
When due to the composition of the Vastu, a Kalā becomes wanting at the repetition, then ॥ the singer ॥ should prolong the Varṇa till this Kalā is completed.
english translation
nivRttau tu kalA nyUnA yadA vastuvazAdbhavet । akAlapAtanAttasyA varNaH kAryo nivRttimAn ॥ 123॥
hk transliteration by Sanscript