SB 6.17.37

iti bhāgavato devyāḥ
 pratiśaptum alantamaḥ
mūrdhnā sa jagṛhe śāpam
 etāvat sādhu-lakṣaṇam
Word for word: 
iti — thus; bhāgavataḥ — the most exalted devotee; devyāḥ — of Pārvatī; pratiśaptum — to make a counter-curse; alantamaḥ — able in all respects; mūrdhnā — with his head; saḥ — he (Citraketu); jagṛhe — accepted; śāpam — the curse; etāvat — this much; sādhu-lakṣaṇam — the symptom of a devotee.
Translation: 
The great devotee Citraketu was so powerful that he was quite competent to curse mother Pārvatī in retaliation, but instead of doing so he very humbly accepted the curse and bowed his head before Lord Śiva and his wife. This is very much to be appreciated as the standard behavior of a Vaiṣṇava.
Purport: 

Upon being informed by Lord Śiva, mother Pārvatī could understand that she was wrong in cursing Citraketu. King Citraketu was so exalted in his character that in spite of being wrongly cursed by Pārvatī, he immediately descended from his airplane and bowed his head before the mother, accepting her curse. This has already been explained: nārāyaṇa-parāḥ sarve na kutaścana bibhyati. Citraketu very sportingly felt that since the mother wanted to curse him, he could accept this curse just to please her. This is called sādhu-lakṣaṇam, the characteristic of a sādhu, or a devotee. As explained by Śrī Caitanya Mahāprabhu, tṛṇād api sunīcena taror api sahiṣṇunā. A devotee should always be very humble and meek and should offer all respect to others, especially to superiors. Being protected by the Supreme Personality of Godhead, a devotee is always powerful, but a devotee does not wish to show his power unnecessarily. However, when a less intelligent person has some power, he wants to use it for sense gratification. This is not the behavior of a devotee.