iOS 9.3.5 (build 13G36) is an official Apple over-the-air update for the iPhone 4s, released on 2016-08-25T16:53:26Z. The update package is 255.55 MB. This is a delta (partial) update that requires 9.0.2 already installed. This update is currently signed by Apple, so it can be applied from Settings › General › Software Update.

Payload file: e2131e44fcdd2aa7e75792fb05ff79aad3ba9794.zip.