Whatever the reason, it’s a matter of attaching the contact information to a chat message.
Here’s how to do that.
In the menu that appears, tapContact.

grab the contact you want to send.
TapDoneon iPhoneor theSendarrow on Android.
The contact opens on the screen.

Tap the checkmark next to any information you don’t want to share to deselect it.
When you’re done, tapSendand the contact card will appear in the WhatsApp chat window.
This is handy if you have a contact on your phone that doesn’t show up on WhatsApp.

Open your iPhone’s Contacts app and tap the contact you want to share.
On the Contact Detail page, tapShare Contact.
In the share options that appear, find and selectWhatsApp.

Choose the WhatsApp contact you want to send the information to.
When you’re done, tapSend.
Open your Android’s Contacts app and tap the contact you want to share.

When the contact opens, tap the Share icon at the bottom of the screen.
Choose whether to share the contact as aFileorTextin the message that appears.
Find and tapWhatsAppin your sharing options.

Tap the contact you want to share the information with, and then tap theSendarrow.
WhatsApp opens with the contact information populated.
Tap theSendarrow to send the information.
But you also may have chosen not to.
Before you could send contacts to other people on WhatsApp, you’ll need to allow contact syncing.
Once you’ve synced your contacts, you could share any of them from your equipment to WhatsApp.