BY A STAFF REPORTER: Defence Minister Rajnath Singh on Friday expressed grief on the demise of Prime Minister Narendra Modi's mother Heeraben Modi. Rajnath highlighted the value of a mother in one's life and said that its void is "impossible to fill". "I am deeply pained by the passing away of Hira Ba, mother of Prime Minister Shri narendra modi. The death of a mother leaves such a void in one's life that is impossible to fill. I express my condolences to the Prime Minister and his entire family in this hour of grief. Om Shanti!" the Defence Minister tweeted.