Source: THE ECSTACY OF LOVE DIVINE (Essence of Narada Bhakti Sutra) by Swami Shantananda Puri Maharaj
To many, these Siddhis come as a natural result of the Sadhana done. A real Bhakta depends solely on the Lord for all his needs.
Once, Jnaneswara, a Yogi and Namadeva, a Bhakta were travelling together in a desert-like region. They were both thirsty. After a long time they came across a well which was very deep and the water was at the bottom. Jnaneswara went into the well, by his yogic powers and standing on the waters drank to his heart's content. When he came up, he smiled at Namadeva triumphantly. Namadeva continued to chant the name of the Lord when suddenly the water in the well welled up and came up to the top. Namadeva was able to take the water in his palms and quench his thirst. He looked at Jnaneswara apologetically with a friendly smile.
Please check these: Excerpts from a discourse by our Sri Sri Muralidhara Swamiji
What is the greatness of Bhakti? One who practices Yoga attains 'siddhis' , one who practices Vedanta enquiry attains 'siddhis', one who practices 'Karmanushtãnas' attains 'siddhis' but the one who is full of devotion does not attain any kind of 'siddhi'. Bhagavãn feels that one who is devoted to Him needs no 'siddhi'. That is because He is the protector ('Rakshaka').