Srimad Bhagavatam Canto 04, Chapter 11, Text 05

SB 4.11.5

sa tan prsatkair abhidhavato mrdhe
ninaya lokam param arka-mandalam
vrajanti nirbhidya yam urdhva-retasah
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
When Dhruva Maharaja saw the Yaksas coming forward, he immediately took his arrows and cut the enemies to pieces. Separating their arms, legs, heads and bellies from their bodies, he delivered the Yaksas to the planetary system which is situated above the sun globe and which is attainable only by first-class brahmacaris, who have never discharged their semen.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
To be killed by the Lord or by His devotees is auspicious for nondevotees. The Yaksas were killed indiscriminately by Dhruva Maharaja, but they attained the planetary system attainable only for brahmacaris who never discharged their semen. As the impersonalist jñanis or the demons killed by the Lord attain Brahmaloka, or Satyaloka, persons killed by a devotee of the Lord also attain Satyaloka. To reach the Satyaloka planetary system described here, one has to be elevated above the sun globe. Killing, therefore, is not always bad. If the killing is done by the Supreme Personality of Godhead or His devotee or in great sacrifices, it is for the benefit of the entity killed in that way. Material so-called nonviolence is very insignificant in comparison to killing done by the Supreme Personality of Godhead or His devotees. Even when a king or the state government kills a person who is a murderer, that killing is for the benefit of the murderer, for thus he may become cleared of all sinful reactions.
An important word in this verse is urdhva-retasah, which means brahmacaris who have never discharged semen. Celibacy is so important that even though one does not undergo any austerities, penances or ritualistic ceremonies prescribed in the Vedas, if one simply keeps himself a pure brahmacari, not discharging his semen, the result is that after death he goes to the Satyaloka. Generally, sex life is the cause of all miseries in the material world. In the Vedic civilization sex life is restricted in various ways. Out of the whole population of the social structure, only the grhasthas are allowed restricted sex life. All others refrain from sex. The people of this age especially do not know the value of not discharging semen. As such, they are variously entangled with material qualities and suffer an existence of struggle only. The word urdhva-retasah especially indicates the Mayavadi sannyasis, who undergo strict principles of austerity. But in the Bhagavad-gita (8.16) the Lord says that even if one goes up to Brahmaloka, he again comes back (abrahma-bhuvanal lokah punar avartino ’rjuna). Therefore actual mukti, or liberation, can be attained only by devotional service, because by devotional service one can go above Brahmaloka, or to the spiritual world, wherefrom he never comes back. Mayavadi sannyasis are very proud of becoming liberated, but actual liberation is not possible unless one is in touch with the Supreme Lord in devotional service. It is said, harim vina na mrtim taranti: without Krsna’s mercy, no one can have liberation.
Srimad Bhagavatam Canto 04, Chapter 11, Text 04
Srimad Bhagavatam Canto 04, Chapter 11, Text 06