SB 4.8.11

na vatsa nṛpater dhiṣṇyaṁ
 bhavān āroḍhum arhati
na gṛhīto mayā yat tvaṁ
 kukṣāv api nṛpātmajaḥ
Word for word: 
na — not; vatsa — my dear child; nṛpateḥ — of the King; dhiṣṇyam — seat; bhavān — yourself; āroḍhum — to get on; arhati — deserve; na — not; gṛhītaḥ — taken; mayā — by me; yat — because; tvam — you; kukṣau — in the womb; api — although; nṛpa-ātmajaḥ — son of the King.
Translation: 
Queen Suruci told Dhruva Mahārāja: My dear child, you do not deserve to sit on the throne or on the lap of the King. Surely you are also the son of the King, but because you did not take your birth from my womb, you are not qualified to sit on your father’s lap.
Purport: 

Queen Suruci very proudly informed Dhruva Mahārāja that to be the King’s son was not the qualification for sitting on the lap or throne of the King. Rather, this privilege was dependent on one’s having taken birth from her womb. In other words, she indirectly informed Dhruva Mahārāja that although he happened to be born of the King, he was considered an illegitimate son because of his birth from the womb of the other queen.