It is narrated from Abdullah bin al-Harith that Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) addressed us on a muddy day. When the mu'adhdhin reached 'Hayya 'alas-salah' (Come to the prayer), he ordered him to say in the adhan: 'As-salatu fir-rihal' (Pray in your dwellings). The people looked at one another, so he said: You are objecting to this; this was done by one (peace and blessings be upon him) who is better than me, and it is among the matters of 'azimah (firm obligation).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 1863