Shiva Purana
अतिसौरभ्यमम्लानं बहुवर्षच्युतं तथा । अन्वीक्ष्य च तयोः कृत्यं भगवान्परमेश्वरः 1-7-२० ।
On seeing the mutual fight of Brahmā and Viṣṇu, lord Śiva laughed. When his head shook, the Ketakī flower dropped down.
english translation
atisaurabhyamamlAnaM bahuvarSacyutaM tathA । anvIkSya ca tayoH kRtyaM bhagavAnparamezvaraH 1-7-20 ।
hk transliteration by Sanscript