The father was an example for the son: "Mahmud ibn Sebuktegin attacks the fortress of Zarang," from a history of the world composed c.1307

Source: http://www.lib.ed.ac.uk/about/bgallery/Gallery/researchcoll/islamicart.html
(downloaded Jan. 2006)

"History of the World, by Rashid al-Din (707 AH, 1307 AD). This superbly illuminated MS history of the world was written in approximately 707 AH (1307 AD), collected by Lt-Col John Baillie, Professor of Arabic Fort William College, Calcutta. It complements the MS formerly in the Royal Asiatic Society's Collections and now in private hands."

Silver coins issued by Subuktigin from the mint at Farwan, 383/4 AH, identifying him as a vassal to Nuh II ibn Mansur

Source: http://ghaznavid.ancients.info/sebuk/sebuk.htm
(downloaded Jan. 2006)