In Chapter 45, Uttarabhaga of Kurma Purana, seven rays of sun is mentioned
सप्तरश्मिरथो भूत्वा समुत्तिष्ठन्दिवाकरः।
असह्यरशिमर्भवति पिबन्नम्भो गभस्तिभिः॥ १४॥
Thereafter, the sun with his seven rays, while rising becomes unbearable with the blazing heat. Through them he drinks up all water present on the earth.
What are the seven rays of sun and what do they signify? In some autobiographies of saints, it is mentioned that yogis can manifest various things due to their mastery over different types of sun rays.