The primary source is the Cisco Software Download portal . You will need a valid CCO (Cisco Connection Online) account and an active service contract (such as SmartNet) associated with your hardware.
Navigate to Switches > Data Center Switches > Nexus 7000 Series Switches and select your specific model to find the 7.3(0)I7(9) release. nxos703i79bin download link
Official Cisco software images are never hosted on public third-party sites for security and licensing reasons. To obtain the legitimate image, you must use the following official channels: The primary source is the Cisco Software Download portal