Final answer:
The exact completion of the quotation directed at Gunatitanand Swami by Shriji Maharaj is not provided in the text given, and therefore cannot be accurately completed without reference to his original teachings or texts.
Step-by-step explanation:
Shriji Maharaj, also known as Lord Swaminarayan, imparted numerous spiritual teachings, among them, a famous quotation directed at Gunatitanand Swami. However, the text provided does not contain the completion of the sentence you're asking about. Therefore, I am unable to complete the quotation "In this life alone, I will destroy the sins of ten million lives of one who ____________." As this is a specific doctrinal or scriptural statement, it is essential to refer to the original texts or teachings of Shriji Maharaj to obtain the correct completion of this quote.