As of now, WhatsApp does not support pinning individual messages within a chat. However, you can pin entire chats to the top of your chat list to keep important conversations easily accessible. Here's how you can do it:

For Android:

1. Open WhatsApp: Launch the WhatsApp application on your Android device.
2. Find the Chat: Scroll through your chat list to find the chat you want to pin.
3. Select the Chat: Tap and hold the chat you want to pin.
4. Pin the Chat: Tap the pin icon that appears at the top of the screen.

For iOS:

1. Open WhatsApp: Launch the WhatsApp application on your iPhone.
2. Find the Chat: Scroll through your chat list to find the chat you want to pin.
3. Swipe Right: Swipe right on the chat you want to pin.
4. Pin the Chat: Tap the pin icon that appears.

Notes:

• You can pin up to three chats.
• Pinned chats will remain at the top of your chat list regardless of new messages in other chats.

If WhatsApp introduces the feature to pin individual messages in the future, it will likely be included in an app update. Keep your app updated to access the latest features.