Learn Icelandic: Fá börn eru þolinmóð þegar þau bíða eftir gjöfinni. - Few children are patient when they wait for the gift.

The verb phrase bíða eftir (to wait for) always requires the noun that follows it to be in the dative case. While eftir can take the accusative case in some other contexts, it strictly takes the dative when used with bíða.

Does eftir usually mean "for"?

On its own, eftir most commonly means "after" or "behind". However, Icelandic prepositional verbs often use different prepositions than English does. The fixed phrase for "to wait for" is always bíða eftir.

How do we get the ending -inni on gjöfinni?

The base word is gjöf (gift), which is a feminine noun. Because it must be in the dative case here, we add the feminine dative singular definite article, which is -inni. This turns gjöf into gjöfinni (the gift).

Why use the pronoun þau for "they" instead of þeir or þær?

Pronouns in Icelandic must match the grammatical gender of the noun they replace. Because börn (children) is a neuter noun, we have to use the neuter plural pronoun þau. You can also see this neuter plural matching in the adjectives fá (few) and þolinmóð (patient).