11. Yarmulka – Head covering:[1]

It is forbidden for one to utter any of G-d’s names without a head covering. Thus, one who recites a blessing must cover his head with a Yarmulka, or any other valid head covering.

May one offer food to Jews who do not wear a head covering?[2] Yes. However one is to instruct them to say a blessing beforehand and it is also proper to propose them to cover their head.[3] If doing so will offend the person then it is not necessary to mention this when offering them food.[4]

Must women cover their head when reciting a blessing?[5] Married women must cover their heads upon saying a blessing or prayer. Single girls are not required to cover their heads upon saying a blessing.

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[1] Admur Basra 2:6; 91:3; 206:7; Michaber 91:3 in name of Yeish Omrim; Beis Yosef 91 that so is the Halacha; Rabbeinu Yerucham 16:7; Miseches Sofrim 14:15; Levush 91:3

[2] Shevet Halevy 8:47; Piskeiy Teshuvos 2:10

[3] It is permitted from the letter of the law to give them food without mention about a head covering however it is best to mention it. However regarding a blessing one must tell them to say a blessing as explained in 169:2. [Shevet Halevy ibid]

[4] See Piskeiy Teshuvos 169:3

[5] See Yabia Omer 6:15; Tefillah Kehilchasa 7:74; Piskeiy Teshuvos 91:2