SB 10.74.4

na hy ekasyādvitīyasya
 brahmaṇaḥ paramātmanaḥ
karmabhir vardhate tejo
 hrasate ca yathā raveḥ
Synonyms: 
na — not; hi — indeed; ekasya — of the one; advitīyasya — without a second; brahmaṇaḥ — the Absolute Truth; parama-ātmanaḥ — the Supreme Soul; karmabhiḥ — by activities; vardhate — increases; tejaḥ — the power; hrasate — diminishes; ca — and; yathā — as; raveḥ — of the sun.
Translation: 
But of course the power of the Absolute Truth, the Supreme Soul, the primeval one without a second, is neither increased nor diminished by His activities, any more than the sun’s power is by its movements.
Purport: 

Śrīla Prabhupāda writes in Kṛṣṇa: “[King Yudhiṣṭhira said,] ‘Your real position is always exalted, exactly like that of the sun, which always remains at the same temperature, both during the time of its rising and the time of its setting. Although we feel the difference in temperature between the rising and the setting sun, the temperature of the sun never changes. You are always transcendentally equipoised, and thus You are neither pleased nor disturbed by any condition of material affairs. You are the Supreme Brahman, the Personality of Godhead, and for You there are no relativities.’”

Śrīla Śrīdhara Svāmī quotes a similar statement from the Vedic mantras: na karmaṇā vardhate no kanīyān (Śatapatha Brāhmaṇa 14.7.2.28, Taittirīya Brāhmaṇa 3.12.9.7 and Bṛhad-āraṇyaka Upaniṣad 4.4.23). “He is not increased by His activities, nor does He become lesser.” As explained here by King Yudhiṣṭhira, the Lord is one without a second. There is no other entity in His supreme category, and thus it is simply by His causeless mercy that He agrees to carry out the orders of His pure devotees, like Mahārāja Yudhiṣṭhira. There is certainly no loss of status for the Supreme Personality of Godhead when He thus extends His causeless mercy to His surrendered devotees.