The Sidh Gohst (Dialogue With The Sages) is a pious Bani that recounts a meeting of Guru Nanak with a group of Hindu ascetics (siddhs) who had renounced the world, living in the caves of the Himalayas. They believed that mental and physical exercises were necessary for acquiring magical powers (also known as siddhis) that would lead to the attainment of liberation.
While such ascetics believed one must withdraw from society and ones family, Guru Nanak's believed that liberation can be attained while living in the world as a truth-oriented 'householder' who earned his living by honest work. For Guru Nanak, true yoga is a meditative remembrance of the Word combined with Seva (selfless service) to those in need in the community.
Guru Arjun Dev collected Guru Nanak's accounts of these meetings and included it (in musical measure) in the Guru Granth Sahib (pages 938-946). The Sidh Gosht recounts Guru Nanak's discourse between Guru Nanak and the Nath yogis Bhangarnath, Chaqrpatnath and Luhairipaa.
Guru Nanak had such discourses with various Yogis during his Udasis, at such places as Achal Batala, Nanakmata and Nanded.