Kṛṣṇa says: "When there is sexual intercourse according to the scriptural injunction, that is I am." Kṛṣṇa says: "I am that sexual intercourse." In such kind of sexual intercourse there is no sin. That is another yajña. Just like we eat kṛṣṇa-prasādam by offering yajña. Yajña-śiṣṭāśinaḥ santo mucyante sarva-kilbiṣaiḥ (BG 3.13). If we take kṛṣṇa-prasādam, then we become freed from all kinds of sinful reaction.
Because the material world is so made that willingly or unwillingly . . . if you are not willing, unwillingly you have to commit so many sinful actions. Just like to kill an animal is sinful action, but you don't want to kill. Still, when you are passing on the street, you are killing so many ants. While drinking water, besides the . . . all around the water jug there are so many animals. When you crush, I mean to say, spices, we kill so many animals.
So we are responsible for that. Because in the Bhagavad-gītā you know, bhuñjate te tv aghaṁ pāpā ye pacanty ātma-kāraṇāt (BG 3.13). If you simply cook for your sense gratification, then you have to take responsibility of all the killing business. But if you offer to Kṛṣṇa and take the prasādam, you become free from the contamination. Similarly, we require to eat, we require to sleep, we require to mate and we require to defend. If these things are done on account of Kṛṣṇa or as enjoined in the śāstra . . .
Śāstra means, as I have already told you, the orders of Kṛṣṇa or orders of God. Sādhu-śāstra-guru. They are the same thing. There is no difference. A sādhu follows the orders of the scriptures. A guru follows the order of the scriptures. And śāstra is description of the Supreme Lord. Just like we are reading Bhagavad-gītā. These are the injunction of Kṛṣṇa. Therefore it is śāstra. Or anyone who writes in terms of the śāstra, that is right direction. If we speak Bhagavad-gītā as Kṛṣṇa desires, then it is right. And if we describe Bhagavad-gītā to fulfil our ulterior motives for some purpose, then it is useless.