In plain words
One who, free from delusion, knows Me thus as Purushottama knows all and worships Me with one's whole being, Bharata.
Word for word
Who, undeluded, thus knows Me as Puruṣottama, he, knowing all, worships Me with [his] whole being, O Bhārata.
यो मामेवमसम्मूढो जानाति पुरुषोत्तमम्स सर्वविद् भजति मां सर्वभावेन भारत
Other commentaries
The commentators
▸Bhagavadgītābhāṣyam
अथ इदानीं यथानिरुक्तम् आत्मानं यो वेद, तस्य इदं फलम् उच्यते —
यः माम् ईश्वरं यथोक्तविशेषणम् एवं यथोक्तेन प्रकारेण असंमूढः संमोहवर्जितः सन् जानाति ‘अयम् अहम् अस्मि’ इति पुरुषोत्तमं सः सर्ववित् सर्वात्मना सर्वं वेत्तीति सर्वज्ञः सर्वभूतस्थं भजति मां सर्वभावेन सर्वात्मतया हे भारत ॥ १९ ॥
In plain words
Now, for the one who knows the Self exactly as it has just been described, here is what follows —
Whoever knows Me, the Lord, exactly as I have just described Myself, free of all delusion, realizing 'this I am,' knows Me as Puruṣottama, the Supreme Person. That person knows everything, because he knows through the very Self of all things, and so he is called omniscient. And he worships Me, present in every being, with his whole being, through the very sense of being the Self of all, Arjuna.
Close to the Sanskrit
Now, at this point, of him who knows the Self just as it has been defined, this fruit is stated —
He who knows Me, the Lord, as characterized as described, thus, in the manner described, being undeluded, free from delusion, 'this I am' — thus knows Me as Puruṣottama; he is the knower of all, since by the Self of all he knows everything, thus omniscient; he worships Me, dwelling in all beings, with his whole being, by the state of being the Self of all, O Bhārata. || 19 ||