Agni Purana (Jyotisha Selections) · by Vyasa
Chapter 2 · War Astrology: Yogas, Nakshatras
युद्धजयार्णवः (योगाः नक्षत्राणि)
सोमाद्धुताशनं वह्नेराप्यमाप्याच्छिवालयम् ।रुद्राद्यमं यमाद्वायुं वायोश्चन्द्रं व्रजेत्पुनः ॥ ३४ ॥
In the full Agni Purana this is chapter 125, verse 34.
From the north to the south-east. From the south-east to the west. From the west to the north-east. From the north-east to the south. From the south to the north-west. From the north-west he goes back to the east.
Simple meaning: Rahu moves through all eight directions in a ring and comes back to the east.
भुङ्क्ते चतस्रो नाड्य(डी)स्तु राहुः पृष्ठे जयो रणे ।
Rahu behind brings victory in battle and Rahu in front brings death.
आग्नेयादि शिवान्तं च पूर्णिमामादितः प्रिये ।
From the full moon on, Rahu moves through the directions, and his look brings victory.
ऐशान्याग्नेयनैर्ऋत्यवायव्ये फणिराहुकः ।
Snake Rahu sits in the corner directions. Death comes where the Sun is in front.