Thanesar (Haryana). Elliot and Dowson, Vol. II : Elliot and Dowson, History of India as told by its own Historians, 8 Volumes, Allahabad Reprint, 1964. p. 40-41 Also quoted (in part) in Jain, Meenakshi (2011). The India they saw: Foreign accounts.
Quotes from Tarikh Yamini (Kitabu-l Yamini) by Al Utbi
Context: The chief of Tanesar was on this account obstinate in his infidelity and denial of Allah. So the Sultan marched against him with his valiant warriors, for the purpose of planting the standards of Islam and extirpating idolatry... The Sultan adopted the stratagem of ordering some of his troops to cross the river by two different fords, and to attack the enemy on both sides; and when they were all engaged in close conflict, he ordered another body of men to go up the bank of the stream, which was flowing through the pass with fearful impetuosity, and attack the enemy amongst the ravines, where they were posted in the greatest number. The battle raged fiercely, and about evening, after a vigorous attack on thepart of the Musulmans, the enemy fled, leaving their elephants, which were all driven into the camp of the Sultan, except one, which ran off and could not be found. The largest were reserved for the Sultan.
The blood of the infidels flowed so copiously that the stream was discoloured, and people were unable to drink it. Had not night come on and concealed the traces of their flight, many more of the enemy would have been slain. The victory was gained by Allah's grace, who has established Islam forever as the best of religions, notwithstanding that idolators revolt against it. The Sultan returned with plunder which it is impossible to recount - Praise be to Allah, the protector of the world, for the honour he bestows upon Islam and Musulmans!...