Rif Brachot 6a

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6a

{From the Mishna:}
"[A PRAYER] WHICH THEY ORDERED TO BE CONCLUDED [WITH A BENEDICTION] MUST NOT BE LEFT WITHOUT SUCH A CONCLUSION;"

{Brachot 12a}
It is obvious that one who takes a cup of wine in his hand, thinking it is beer, begins with the blessing of beer {Shehakol} and finishes with the blessing of wine {HaGafen} fulfills his obligation, for even if he finished with the blessing of beer has fulfilled, for we have learnt: and on all of them if he says Shehakol Nihyah Bidvaro he has fulfilled.
But one who takes a cup of beer in his hand, thinking it is wine, begins with the blessing of wine and finishes with the blessing of beer, then what?
Do we go after the opening or after the ending?
And we do not resolve {this question}, and we act leniently, and we do not go back, for in a case of doubt in Rabbinic law we rule leniently.

We learnt in a brayta: in the morning, one who opened with yotzer `or {the appropriate blessing during the day} - and ended with ma'ariv 'aravim {the appropriate blessing during the night} - he did not fulfill {the obligation. During the day} if he opened with ma'ariv 'aravim and ended with yotzer `or fulfills. In the evening, if he began with ma'ariv 'aravim and ended with yotzer `or he did not fulfill; if he opened with yotzer `or and ended with ma'ariv 'aravim he did fulfill. The rule of the matter: all goes after the ending.

What if meant to be included by "all?"
To include on who ate dates and thought he ate bread, began the blessing for bread and finished with that of dates has fulfilled; or, if he {ate dates and} started with {the blessing} for dates and ended with that of bread has fulfilled.
What is the reason?
Because dates also give sustenance.

Rabba bar Chanina Sava cited Rav: One who does not say Emet Veyatziv {the paragraph after Shema} in the morning