Brahma Sutras
ॐ प्रतिज्ञासिद्धेर्लिङ्गमाश्मरथ्यः ॐ ॥ १-४-२०॥
Asmarathya thinks this (statement of non-difference between the individual soul and supreme Self) to be a sign indicative of the fulfilment of the declaration.
english translation
OM pratijJAsiddherliGgamAzmarathyaH OM ॥ 1-4-20॥
hk transliteration by Sanscript