What should be worn when one is davening Shemoneh Esrei?

A person may only daven Shemoneh Esrei when he is fully clothed. One who is standing before the King must be in a state of awe, which would call for him to be fully covered. L’chatchilah, one should also be fully covered when saying Kriyas Shema or a brocha. Under pressing conditions, one may say Shema or a brocha as long as he is covered from the waist down.

סימן עד ס"ו ס"ק כא-כג

Are there restrictions for a person who is davening in front of his wife?

Ervah includes any area on a woman’s body which is generally covered. One is forbidden to say a davar shebekedusha in front of an exposed body part of this kind, even if it is his wife’s or his daughter’s. These areas are classified as ervah because seeing them can bring a person to improper thoughts. Shulchon Aruch rules that saying a davar shebekedusha is only forbidden if a tefach of the area is exposed. Rema says that when seeing a woman other than one’s wife, reciting a davar shebekedusha is an issue even when less than a tefach is exposed. The poskim disagree about whether the tefach area is defined as a square tefach or whether it also includes a tefach of uneven dimensions (e.g. the length is longer than a tefach and the width is shorter). Some say that even a tefach in one dimension is an ervah.

סימן עה ס"א ס"ק א ביאורים ומוספים דרשו 9

At what age does the obligation of tznius begin?

The poskim disagree on whether closing one’s eyes when facing an ervah is sufficient to allow one to say a davar shebekedusha. A person may be lenient if there is no option to turn away. A person must be mindful not to say a davar shebekedusha if there are immodestly dressed women within view, even if he is not focusing on any of them. According to the Biur Halacha, the halachos of dressing properly and restrictions regarding devarim shebekedusha begin when a girl turns three. Chazon Ish disagrees and maintains that there is no uniform age. Instead, these halachos go into effect whenever a girl is feminine enough that being improperly covered would elicit improper thoughts in those who view her. Some say that even in the Chazon Ish’s view, a girl should be dressed properly from the age of three for the sake of chinuch. The general custom is to follow the opinion of the Chazon Ish.  

סימן עה ס"ק א' ביה"ל ד"ה טפח וד"ה במקום ביאורים ומוספים דרשו 4 15

• For the purpose of covering one’s ervah, water suffices even if it is clear. As long as one is not gazing at his ervah, he may recite a brocha. If the water reaches his heart, he must also place a garment or cloth on or below the heart to separate it from the ervah.

• A person may only recite a brocha or davar shebekedusha if his head is covered. It must be covered by something other than his hand, since the body cannot cover itself.

• A person who touches the areas of his body which are normally covered must wash his hands before reciting a davar shebekedusha. The concern is that these areas can be dirty and can soil the hands. The poskim disagree about whether this halacha applies if one touches an area that he is certain is clean.

• Guarding one’s eyes properly

• Where must a married woman cover her hair?

• Is wearing a wig permitted?