From where do I derive this; for we learnt, ‘this calf’, etc. - מנא אמינא לה דתניא עגל זה
Summary:
We can derive from the ברייתא of עגל that שומא is needed to achieve trust, however we cannot derive from this ברייתא that שומא is needed to achieve קיץ.
רב כהנא took a headscarf for פדיון הבן, etc. - רב כהנא שקל סודרא בפדיון הבן
Summary:
There were two אמוראים called רב כהנא; one was a כהן and one was not. Alternately there was only one רב כהנא and he enjoyed the privileges of פדה"ב and מתנות כהונה because he was married to a כהנת and he maintained that a כהנת receives מתנות כהונה and can redeem the בכור.
Summary:
A מתנה ע"מ להחזיר is considered a gift in the amount given (even though it is returned); however by לדידי חזי לי is not considered as if the named amount was actually given.
Now if by מנה סתם it is not a valid קידושין; is מנה זו necessary - השתא במנה סתם לא הוו קידושין במנה זו מיבעיא
Summary:
Once we realize that by מנה סתם there is no קידושין until the entire מנה is paid, we also realize that by מנה זו and it was a חסר, there can never be קידושין.