Bhashya
यत्तु एकैकमक्षरम् एकैकस्मिन्पत्रे तत्प्रणवसंपुटितं कार्यम्, 'प्रत्यक्षरमुभयत ओंकारो भवति' इति श्रुतेः ।तदस्त्राख्यमङ्गं महाचक्रमुपासितं तन्निक्षिप्तमनिष्टे वस्तुनि त्रासकारित्वात् तदस्त्रं पञ्चममङ्गम् ।अत एव अस्त्राङ्गमन्त्रं व्याचक्षाणैरस्माभिरुक्तं प्रपञ्चसारे—'असुत्रासादिकौ धातू स्तः क्षेपचलनार्थकौ ।ताभ्यामनिष्टमाक्षिप्य क्षिप्यते फट्खड्गिना' इति ।सार्वकामिकं मोक्षद्वारमित्युक्तार्थम् ।ऋङ्मयं यजुर्मयं साममयं ब्रह्ममयममृतमयं भवतीति पञ्च मयट्प्रत्ययाः प्राचुर्यार्था ग्राह्याः ।ऋग्यजुःसामाथर्वप्रचुरम् ।ब्रह्ममियमिति ब्रह्मशब्देन अथर्ववेदः सोऽयं ब्रह्म वेद इत्येतद्ब्राह्मणाभिधानात् ।वेदप्रचुरता अराणां वेदबुद्धयोपास्यत्वात् ।विकारार्थो वा मयट् वेदविकारात्मका इत्यर्थः ।अमृतमयं क्षीरप्रचुरनाभिकं क्षीरविकारनाभिकं वा इति ।तस्येति तच्छब्दान्नाभिस्थो विष्णुः मूलनृसिंहव्यूहः परामृश्यते ।तत्परिचारकान्देवानाह—पुरस्ताद्वसवः परिचारका आसते रुद्रा दक्षिणत आदित्याः पश्चाद्विश्वे देवा उत्तरतो ब्रह्मविष्णुमहेश्वरा नाभ्यामिति ।एवं दिङ्नाभिपरिचारकानुक्त्वा अथेदानीं पार्श्वपरिचारकानाह—सूर्याचन्द्रमसौ पार्श्वयोः कुक्षिप्रदेशयोरिति यावत् ।तदेतन्महाचक्रम् ऋचा अभ्युक्तम् ।
In plain words
The rule for placing each syllable on its petal is this: wrap the praṇava around it, syllable by syllable — the Śruti itself says so: 'Om stands on both sides of every syllable.' That is the Weapon-limb, worshipped as part of the Great Wheel — called that because, once released at an unwanted target, it strikes terror into it. This fifth limb is the very mantra we explained ourselves in the Prapañcasāra: two roots, asu and trās, meaning to hurl and to shake, so that the unwanted thing is seized and struck down by phaṭ in the hand of the sword-bearer. It grants every wish — it is the door to liberation, as already said. Five times the syllable is called 'consisting of' something: the Ṛg, the Yajus, the Sāma, brahman, the immortal — and each of those five means simply 'abounding in': the wheel is rich in Ṛg, Yajus, Sāma, and Atharva alike. 'Consisting of brahman' points to the Atharvaveda, since a brāhmaṇa text itself calls that same Veda 'the veda of brahman'. The spokes carry this Vedic abundance because they are meditated on as the Vedas themselves — or, on another reading, 'consisting of' means 'transformed from': the spokes are transformations of the Veda. And 'consisting of the immortal' means the navel is rich with milk, or itself a transformation of milk. The word 'of it' points back to Viṣṇu at the navel — the root Nṛsiṃha array, named again. Then the text names his attendants: the Vasus stand in front, the Rudras to the south, the Ādityas to the west, the Viśvedevas to the north, and Brahmā, Viṣṇu, and Maheśvara right at the navel. With the four directions and the center accounted for, it turns to the two flanks: the sun and the moon, standing at the belly on either side. All of this — the whole Great Wheel — has already been laid out in a single verse.
Close to the Sanskrit
As for the point that one syllable each is to be enclosed by the praṇava on each single petal — on the authority of the Śruti: 'On both sides of every syllable there is the syllable Om.' That, called the Weapon-limb, worshipped as part of the Mahācakra, because of its capacity to strike terror into an undesired object when discharged, that weapon is the fifth limb. For this very reason, the weapon-limb mantra was stated by us, in explaining it, in the Prapañcasāra: 'The two roots asu and trās, meaning 'to hurl' and 'to move' — by these two, the undesired thing, having been assailed, is struck down by phaṭ wielding the sword.' It fulfils every desire, being the gateway to liberation — that was already stated as the meaning. 'Consisting of the Ṛg, consisting of the Yajus, consisting of the Sāma, consisting of brahman, consisting of the immortal' — thus the five occurrences of the suffix mayaṭ are to be understood in the sense of abundance: abounding in Ṛg, Yajus, Sāma, and Atharva. 'Consisting of brahman' — by the word 'brahma' is meant the Atharvaveda, because this same [veda] is called 'the veda of brahman' in the brāhmaṇa-text. The abundance of the Veda belongs to the spokes, because they are meditated upon through the notion of the Veda. Or, the suffix mayaṭ has the sense of transformation — meaning, they are made of transformations of the Veda. 'Consisting of amṛta' means having a navel abounding in milk, or having a navel that is a transformation of milk. By the word 'of it' — [that is,] the word 'tat' — Viṣṇu situated at the navel, the root Nṛsiṃha array, is referred to again. [The text] speaks of his attendant deities: in front sit the attendant Vasus; the Rudras to the south; the Ādityas to the west; the Viśvedevas to the north; Brahmā, Viṣṇu, and Maheśvara at the navel. Having thus named the directional and navel attendants, now, next, [the text] speaks of the flank attendants: the sun and moon at the two flanks, meaning at the two belly-regions. This same Mahācakra has been described by a verse.