I found this thread already https://learn.microsoft.com/en-us/answers/questions/723406/copy-azure-service-bus-messages-in-queue-to-data-l, so I will help you with some code in Python.
import azure.servicebus
from azure.servicebus import ServiceBusClient, ServiceBusMessage
# Replace with your connection string
connection_str = "YOUR_SERVICE_BUS_CONNECTION_STRING"
queue_name = "YOUR_QUEUE_NAME"
# Create a Service Bus client
with ServiceBusClient.from_connection_string(connection_str) as client:
# Send messages to the queue
with client.get_queue_sender(queue_name) as sender:
msg = ServiceBusMessage("Hello, Azure Service Bus!")
sender.send_messages(msg)
print("Message sent!")