NIHĀL SIṄGH, SANT, also known as Paṇḍit Nihāl Siṅgh, a Sanskrit scholar well versed in Vedānta as well as in gurbāṇī, lived in Sikh times in the village of Thohā Khālsā, in district Rāwalpiṇḍī, now in Pakistan. Paṇḍit Nihāl Siṅgh is famous for his Sanskrit commentary on Japu, the Japugūḍhārthadīpakā (Lamp which illuminates the deep and hidden meaning of the Japu) patterned on Śaṅkar's Bhāṣya on Vedāntasūtra. According to the colophon appended to the manuscript, work on Gūḍhārthadīpakā was undertaken at the instance of an Udāsī saint, Bavā Buddh Sarūp. One Paṇḍit Chandar Bhān Kashmīrī acted as the scribe. The manuscript, completed in 1839, has not been published. The only extant copy, which is said to be the original one, is preserved in a private collection in Paṭiālā. The manuscript is written in a good clear hand and runs into 103 sheets, 131/4"X531/2", with twelve to thirteen lines to a page.
In the Japugūḍhārthadīpakā, the original text in Gurmukhī is reproduced in Devanāgrī characters. Then comes ṭīkā or paraphrase, followed by explanation or commentary.
The transliteration of the Japu into Devanāgrī script is somewhat arbitrary. Vowel symbols used in the original Gurmukhī have been omitted or altered. Some Punjabi words have been transcribed in their original Sanskrit form, e.g. the original sati has been changed to satya, purakhu has been changed to puruṣa. There are some plain errors as well, e.g. gurā ik dehi bujhāī has been written as Guruā ik deh bujhāī (stanza VI of the Japu). At places, lines from the original text are missing. The commentary is coloured by Paṇḍit Nihāl Siṅgh's background in Advaita. He is by faith a Sikh, but his interpretation of the Japu has an emphatic Vedantic bias. In the inaugural passages, Nihāl Siṅgh invokes the Hindu deities and incarnations such as Śrī Gaṇeśā, Śarasvatī and Śrī Kṛṣṇa. One Sobhā Siṅgh Indraprasthī translated the Japūguḍhārthadīpakā into highly Hindized Punjabi, under the title Japu Nibandh Gūḍhārthadīpakā Ṭikā, an incomplete manuscript copy of which is preserved in a private collection at Amritsar.