Narada Purana (Jyotisha Selections) · by Vyasa
Chapter 2 · Signs, Planets, Birth
जातकम् १
वींद्वर्का विकुजेंद्वर्काः सुहृदोऽन्ये रवेर्धृताः ।मिथोधनव्ययायत्रिबंधुव्यापारगः सुहृत् ॥ २६ ॥
In the full Narada Purana (Purva Bhaga) this is chapter 55, verse 26.
Venus's friends are all but the Moon and the Sun. Saturn's are all but Mars, the Moon and the Sun. Some hold these as the friends, from the Sun on. Planets in the 2nd, 12th, 11th, 3rd, 4th and 10th from each other are friends.
Simple meaning: Planets in the 2nd, 3rd, 4th, 10th, 11th or 12th from each other are friends for the moment.
स्वोच्चत्रिकोणगेहा प्रनवांशैस्थानजं बलम् ।
A planet is strong in its high sign, own sign and own navamsha. It also gets strength from a direction.
निशींदुकुजसौराश्च सर्वदा क्षोह्नि चापरे ।
Moon, Mars and Saturn are strong at night. The rest are strong by day. Bad planets gain in the dark half.
सौरारज्ञेज्यशुक्रेंदुसूर्याधिक्यं परस्परम् ।
The planets go up in strength from Saturn to the Sun. Good planets count when they stand in a corner house.