It doesn't necessarily praise Advaita, but it says that followers of that Yoga will be rewarded with bliss, be freed from the burdens of life, etc. This is a line from the Garuda Purana (Dhanvantari Samhita- Chapter 246):
There are two kinds of Yogas, viz., the Advaita Yoga and the Sankhya Yoga, the absolute concentration of the mind being the essential factor in both these forms. Practisers of the Advaita Yoga become free from the shackles of existence. Past, present and future acts are destroyed through knowledge. He, who hews down the tree of existence with the axe of right discrimination and takes an ablution in the sacred pool of knowledge and apathy, comes by the bliss of Vishnu.
It's the only Puranic line I could find that explicitly commends Advaita and tells us that it's a good practice.
That said, there's another set of verses from the Garuda Purana that explain: dual/non-dual is not the point, the point is understanding the collectiveness of the universe.
The word from the Teacher gives liberation; all learning is masquerade. Among thousands of woods the Sañjīvana is best.
The non-dual, verily declared auspicious, is beyond efforts of action, and to be obtained by the word of the Teacher, not by the study of tens of millions of texts.
Knowledge is said to be of two kinds: study and discrimination. The study is of Śabda Brāhmaṇ; Para Brahmaṇ is reached by discrimination.
Some prefer the Non-dual; other prefer the Dual but they do not understand the One Reality, beyond the Dual and Non-dual.