ya āśu hṛdaya-granthiḿ
nirjihīṛṣuḥ parātmanaḥ
vidhinopacared devaḿ
tantroktena ca keśavam
yah -- one who; asu -- quickly; hridaya-granthim -- the knot of the heart (false identification with the material body); nirjihirshuh -- desirous of cutting; paratmanah -- of the transcendental soul; vidhina -- with the regulations; upacaret -- he should worship; devam -- the Supreme Personality of Godhead; tantra-uktena -- which are described by the tantras (the supplementary Vedic literatures that give detailed instructions for spiritual practice); ca -- as well (in addition to those regulations which are directly vedoktam); kesavam -- Lord Kesava.
The Vedic literatures contain mysterious descriptions of the Absolute Truth that stimulate philosophical speculation. The Vedas also offer heavenly rewards for the performance of ritualistic ceremonies. But as stated in verse 44 of this chapter such jnana-kanda and karma-kanda sections of the Vedas are balanam anusasanam; that is, because less intelligent or childish persons are addicted to mental speculation and fruitive activity, these sections of the Vedas are meant to attract such persons to take shelter of the Vedic injunctions for gradual promotion to the perfect stage of Krishna consciousness.
Now that the path for those who are materialistic has been described in several verses, this verse describes the process for those who are vijnah, or learned transcendentalists. Such learned transcendentalists are advised to follow the regulated worship described in such Vaishnava tantras as Sri Narada-pancaratra for pleasing the Supreme Lord directly. The words upacared devam tantroktena ca kesavam indicate that one should directly worship Kesava, the Supreme Personality of Godhead, who appears in many different incarnations to please His devotees. Srila Jayadeva Gosvami has described the pastimes of the Lord in his song describing ten prominent incarnations of the Personality of Godhead, Kesava: Lord Fish, Lord Tortoise, Lord Boar, Lord Nrisimhadeva, Lord Vamana, Lord Parasurama, Lord Ramacandra, Lord Balarama, Lord Buddha and Lord Kalki. The words upacared devam indicate devotional service to the Personality of Godhead. And therefore the word tantroktena, or "injunctions of the tantras," should be understood to indicate vaishnava-tantras such as Sri Narada-pancaratra, which give explicit and detailed instructions for worshiping Kesava. The Vedas are referred to by the term nigama. And the elaborate explanation of these nigamas is called agama, or tantra. When the transcendental living entity becomes perturbed by the obnoxious harassment of material bodily dualities, he becomes eager to hear from the Vedas about his transcendental situation. The word asu in this verse indicates that those who are eager to put a quick end to material existence and situate themselves in the eternal blissful life of perfect knowledge should directly worship Lord Krishna, bypassing the preliminary Vedic rituals described in the previous verses.