Chennai, Oct 9 : Actor Madhavan, who is basking in the success of his critically acclaimed superhit film, 'Rocketry: The Nambi Effect', has penned an adorable birthday post for his sister Devika, who celebrates her 50th birthday on Sunday. Taking to Instagram to express his wishes, the actor, while posting a picture of him together with his sister, wrote: "Wishing a happy 50th birthday to one of the most generous caring and nicest souls I have ever known." "Someone who works tirelessly for everybody else without expecting a whisper of gratitude. It's been such a privilege being your brother for 50 years and I pray for 50 more for the sake of everybody else in this family." "Devika, you are an inspiration and even though I may not show or say it enough, you've always been one. Love you, Tangachhi. Happy birthday again." The picture posted by Madhavan for the post has also been winning appreciation. Well-known classical musicians Ranjani and Gayathri too responded to Madhavan's post. They said: "Happy Birthday wishes to Devika! What a lovely pic!" /IANS