[Event Monitoring suggests using `transfer()`](https://consensys.github.io/smart-contract-best-practices/development-recommendations/solidity-specific/event-monitoring/) but [External Calls warns against it](https://consensys.github.io/smart-contract-best-practices/development-recommendations/general/external-calls/#dont-use-transfer-or-send). > Patterns like `require(msg.sender.send(1 ether))` can also be simplified to using `transfer()`, as in `msg.sender.transfer(1 ether)`. > Don't use `transfer()` or `send()`.