Assumption used: the user wants a complete, practical article describing WhatsApp for Android devices and how to safely obtain the correct download link.
If you need an older specific version for compatibility testing, APKMirror is the industry standard. They cryptographically sign every APK to match the official signature. android 23 6 whatsapp download link
If you are searching for a specific download link because you have an older phone, you must be aware of the current support requirements. Assumption used: the user wants a complete, practical
Minimum Requirement Changed (Oct 24, 2023): WhatsApp officially ended support for Android versions 4.x and 5.x (Lollipop and KitKat). android 23 6 whatsapp download link