احسن الله إليكم Is it permissible to say "Aḥsan Allāhu ilaykum" to fellow readers or Muslims in general, or is it only for the mashaykh and ṭullāb al-ʿilm, and should it be avoided with a recipient who fears riyā'? بارك الله فيكم

Ustadh AbdulAziz al-Haqqan

Yes, you may say it to anyone.