The brothers Tejpal Singh (b. 1937) and Surinder Singh (b. 1940), popularly known as “Singh Bandhu,” cut their musical teeth under their elder brother G.S. Sardar. Later, Surinder Singh took taleem from N. Aminuddin Dagar. In 1961, both the brothers became pupils of Amir Khan. The time spent at the feet of the great ustad was to play a major role in the transformation of their respective musical personalities. The Singh brothers are also adept at devotional music, and have an association with not only with the shabads of the Sikh gurus, but also with the works of the Sufi saints and the Bhakti saints of south India.
Reference: Bharatiya Sangeetkar Ustad Amir Khan by Ibrahim Ali (Classical Publishing Company, New Delhi, 2000)