Hazrat Shaykh Muhammad Zakariyya Kandhalawi Muhajir-e-Madani has written in Fadhaaile-Durood - Virtues of Salaat and Salaam: There are however times when it is undesirable (‘makrooh’) to send Durood. This includes : 1. During intercourse. 2. Whilst retrieving one-self from the call of nature. 3. For advertising the sale of product. 4. Whilst stumbling. 5. During astonishment. 6. Whilst slaughtering an animal. 7. Whilst sneezing.